|“||Because I am a Shadowhunter.||”|
Mark Blackthorn, also known among some fey as Miach, is a Shadowhunter residing at the Los Angeles Institute and is one of the many Blackthorn children. He was a former Hunter who rode with the Wild Hunt. He and his older sister, Helen, have the same faerie mother and are half-faerie.
Born to a Seelie Court faerie Lady Nerissa and Andrew Blackthorn in 1991, Mark and his older sister, Helen, were raised at the Los Angeles Institute with their father, and, like ordinary Shadowhunter children, were Marked when they were ten years old, during which Mark experienced some pain—a bit more than most Shadowhunters. Mark has five younger half-siblings: Julian, Livia, Tiberius, Drusilla and Octavian.
Despite being their half-brother, Mark had a generally good relationship with his younger siblings. He was even one of the few people who managed to get through to Ty during his bad moods.
As children, the siblings, including family friend Emma Carstairs, spent many rainy days making pillow forts. At ten years old, Mark was considered the proverbial "pillow fort expert", and the others would build the forts under his supervision.
Mark was around sixteen in 2007 when Sebastian Morgenstern and his army of Dark Shadowhunters attacked the Institute. Mark was on secondary supervision and was at the training room with the children and their tutor, Katerina. When the commotion began, Mark and Katerina left to investigate the situation. There, they joined the ongoing fight between the Conclave members and the Endarkened. Katerina and Mark's father, Andrew, were Turned into Endarkened while Mark, who was originally meant to be Turned into Endarkened as well, was ultimately taken to the Fair Folk when Jonathan realized Mark was half-fey.
When the faeries were deciding on Mark's fate, Gwyn ap Nudd claimed him, and, after some time suffering through Meliorn whipping and torturing him, Mark was led to believe that his family was dead, so he ate and drank the faerie food he was offered so Meliorn would stop hurting him. Mark accepted that he no longer had a family to return to and officially became a Hunter of the Wild Hunt, causing one of his eyes to turn gold. Being in Faerie, time flowed differently, and, though Mark had not been missing from his home longer than a week, he felt as though he had been with the Hunt for a seemingly long time. Regardless, thoughts of his family never left him.
During one of his visits to the Seelie Court with Gwyn and the other Hunters, he overheard some fellow hunters talking about how Gwyn had witnessed Clary Fray, Jace Herondale, Alec and Isabelle Lightwood, and Simon Lewis arriving to talk to the Seelie Queen. He snuck away from the Hunters to the tunnel that led to Edom so he could meet them and ask about his family. Though Clary and Jace informed him that his siblings were alive, Mark felt devastated, knowing that he can no longer leave the Hunt to be with them. Nonetheless, Mark asked to go with them so he could reunite with his family, but Jace stopped him and reminded Mark that he had already sworn fealty to the Hunt and may face death if he tried to leave. Instead, Jace convinced Mark to simply warn the Shadowhunters of the faeries' conspiracy. Initially scared, Mark agreed. Before he left, Jace gave him his witchlight to help him metaphorically continue to see the light, even in the darkness.
Soon enough, Mark sent a message to the home of the Consul, which was coincidentally where his siblings were staying. He put the message in an acorn, in typical faerie fashion, stuck it to a fire poker, and shot it through their window. A pleased Ty found the message and gave it to Jules and Emma, who passed it onto the Consul, Jia Penhallow. Jules was able to confirm that the message was from Mark because he signed it with a blood stamp of their family ring. Jules and Emma insisted that the Consul try and get Mark back for them.
After the Dark War, because of their faerie blood, some Clave members, particularly Lazlo Balogh and Andrea Sedgewick, questioned Mark and Helen's loyalties to the Nephilim and proposed that they discuss their fate. The majority of the Clave members, most of whom were furious and unforgiving about the fey's betrayal, voted to abandon the efforts to secure Mark's return, despite his family's objections. Similarly, his half-fey sister, Helen, was exiled to Wrangel Island under the guise of being sent to study the wards.
For years after he was taken from them, Mark's room at the Los Angeles Institute was left untouched. Finally, on his eighteenth birthday in 2009, Julian cleaned out the room, putting all of Mark's belongings in boxes in storage. Though the room was vacant, it remained empty and untouched for years after.
Around this time in the human world—and much longer for Mark in fey time—Ascendant Simon was taken to the Faerie. When he found out that Simon was to be Nephilim, he helped Simon escape imprisonment from Hefeydd, asking him about his family before he left. Mark did not care that he was caught helping Simon and Isabelle escape.
In August 2012, Mark was returned to the Blackthorns as a bargaining chip. Iarlath and Kieran took him to the Los Angeles Institute and offered to return Mark to the Blackthorns if they helped investigate the recent murders of the faeries—a transaction that must be kept from the Clave as it went against the Cold Peace. The deal was if the one responsible for the faerie deaths was brought to them for justice, Mark would be allowed to choose if he would return to the Hunt or to his family.
Unbeknownst to them, Mark was returned knowing his presence would ensure that the deal would not reach the Clave, and thus the children would be unable to call them for help and the Guardian's plans would proceed unobstructed.
While Mark initially had some trouble adjusting to Shadowhunter life with his family and yearned for the freedom of the Hunt, Mark soon began to ease into it and bonded with the Institute guest Cristina Rosales, who helped him to deal with the situation. He and Kieran had the occasional secret rendezvous, but during one scheduled visit, Kieran found him and Cristina and suspected their bond as being more than friendly.
Taking a casually dropped story he told Cristina about faeries, Kieran reported him to Iarlath, telling him that Mark had spilled faerie secrets to a Shadowhunter. Iarlath decided his punishment to be twenty whippings, something Kieran, who only hoped to have Mark returned to the Hunt, did not anticipate. Not wanting Mark to break, Julian and later Emma took the whippings for him. This incident made Mark see Kieran in a different light, blaming him for Jules and Emma's pain and began to treat him with contempt, essentially "breaking up" with him. After this, Mark told Jules that he had made up his mind: that he will stay with his family and not return to the Hunt.
They learned that Malcolm Fade was the murderer—of Emma's parents, and the one behind the recent supernatural murders they were investigating—a bit too late as he had already kidnapped their brother, Tavvy, for the ritual. Kieran insisted on helping them and informed them that Iarlath was in league with Malcolm. Wanting to be fully prepared, Mark asked Jules to Mark his skin with a rune—something he constantly went against during their first few trips. Together, they all went to the convergence site to confront Malcolm and battled his minions to rescue Tavvy.
After they defeated Malcolm, the destruction of the convergence site alerted the Clave of his necromantic activity. The Inquisitor, Robert Lightwood, came to the Institute, and Mark's presence was excused when Julian, and even Diego, lied about the circumstances surrounding their investigation and his return. When Ty told him that him staying meant he could finally replace Jules and take over his responsibilities, Mark felt overwhelmed and refused. Mark felt that he'd hurt Ty through his words and tried to find solace in Cristina, but was stopped short when he saw her kissing Diego. These made Mark suddenly regret his decision to stay.
Later, Emma asked Mark to pretend to be in a relationship with her for Julian's sake. He agreed but questioned if they have to lie and fake it. They kissed, but Mark stopped when Emma began crying. He trusted Emma's reason—that it was because of Julian's concern about her on-and-off relationship with Cameron Ashdown, though he told Emma to at least inform Cristina.
To keep up the pretense that they were dating in front of his family, Mark and Emma spent a lot of time together, especially at night when he would sleep in her room—though he would sleep on the floor and let Emma take the bed. They spent those nights talking about various things, but Mark avoided discussing Cristina.
Shortly after, Gwyn came to him and told him that Kieran was set for execution at the Unseelie Court. Though Mark at first refused to save him, he was unable to resist; he snuck out of the Institute one evening and took the moon's road to Faerie. He was followed by Emma, Jules, and Cristina, with help from the latter's medallion. In the Unseelie Lands, they noticed parts of the land affected by a mysterious blight.
While resting one afternoon, he and Cristina were led away from their camp and found themselves at a revel. He and Cristina indulged in the festivities; they drank—regular juice, which Mark made sure of—and danced. Unbeknownst to them, a faerie at the revel placed a binding curse upon them when their wrists were tied with a ribbon. At one point they decided to take a break from the revel and the pair shared a kiss. Mark then learned that Cristina kissed him believing she was under the influence of a faerie drink, which hurt and angered Mark. As Cristina tried to apologize and explain that she did like him, she accidentally told Mark that his Emma's fake relationship was because Julian was in love with Emma.
Realizing that he was hurting his brother, Mark immediately told Emma he wanted to end things. Though she initially disagreed, she respected his wishes and, upon their return, Emma announced to the family that they had broken up.
That evening they rescued Kieran from execution. Being badly injured, Mark was forced to carry and support him as they escaped. Through Kieran's confused ramblings, Mark found out that Kieran did not remember betraying him or their break-up. As they tried to outrun the King's men, they were saved by Mark's aunt Nene in the Seelie Court. She took them into a spare room and got to work on healing Kieran.
Soon they had an audience with the Queen. She offered them the means to end the Cold Peace and in turn, the return of their sister Helen, if only they bring her the Black Volume of the Dead. She wished Kieran to be her messenger to the Clave to deliver her offer of an alliance in taking down the Unseelie King. Kieran initially swore an oath of fealty to Mark but after Julian said no because love complicates things, he chose Cristina, mainly—as Mark suspected—to annoy him. With Mark on the back of Windspear with Kieran, they all flew with the Wild Hunt to return to their family.
Upon arriving at the London Institute and talking everything over, it was decided that Mark would have to pretend to still be in a relationship with Kieran. He hated lying but he understood it was the only way to ensure Kieran would testify so they could get Helen back. Kieran quickly noticed Mark's distance though and Mark used the explanation Cristina had given him when he confided in her at the Seelie Court: that he had spent his whole time in the Hunt needing Kieran, he had not had time to think if they were good for each other and that he would have chosen him otherwise. Kieran begrudgingly understood and allowed Mark space to try to understand what they meant to each other.
However when the binding spell between Mark and Cristina was discovered, Kieran became jealous and upset; accusing them of having gotten it done on purpose. Not long after, Magnus Bane and his family arrived an Magnus immediately got to work on breaking the spell. Though Kieran apologized for the accusation and agreed to speak to his brother Adaon about how to break such a spell, Kieran's jealousy remained and caused even more of a strain between them.
Over the next few days, while Julian was away, Mark was in charge of his siblings. So when the Riders of Mannan were discovered to be after them, Mark did everything he could to find Livvy, Ty, and Kit, who had been out retrieving ingredients for the antidote to the binding spell. After realizing nothing they had could be used to track them, Mark used Diana's acorn, calling on Gwyn and risking his anger to ask for his help. Despite his unhappiness, Gwyn relented and agreed to find them, and indeed saved their lives and brought them back to the Institute.
That night, while trying to reach out to his brother, Kieran got his memories back. Kieran, reasonably hurt and angry, stormed off. Mark, following Cristina, found him hiding in the Sanctuary and asked to speak with him. Mark explained that he did not hate him, in fact he had forgiven him and still loved him. That he had planned to tell him immediately after the testimony as he hated lying to him. During the talk, he also confessed that he does love Cristina. Kieran then said that he believed him and based on his talk with Cristina, he understood that he was simply desperate fore his sister back. Kieran continued to say that he would testify to make up for what he did to Julian and Emma as now he and Mark's debts were paid and, following the testimony, they would be done with each other. Mark attempted to protest but they were interrupted by the arrival of the Riders.
In the ensuing battle, Mark went after Delan first. He was later seen fighting alongside the twins trying to clear the Riders from blocking the entrance. However, by the end of the battle, Mark was caught with Eochaid's sword to his back. Luckily Annabel Blackthorn came sweeping into the courtyard and took their attention away with a show of the Black Volume. Magnus soon joined them as well and dispatched the Riders of their weapons, causing them to flee.
At the meeting in Alicante, Mark became concerned for Kieran's safety, especially after the appearance of the Cohort. Cristina assured him he would be fine as she had a plan in place. When Helen arrived in the Hall, Mark enveloped her in a big hug. Mark mentioned having met their aunt and they made plans to truly talk and catch up that night. However the meeting took a horrific turn resulting in Annabel killing the Inquisitor Robert Lightwood and Livvy. Ty fainted after Livvy fell and Mark went, trembling, to him.
Following Livvy's death, Mark was tasked with breaking the news to Tavvy. It did not go well and Mark became very upset that he could not do more to help as he barely knows his family. At the funeral he tried to make conversation with his siblings and comfort them but he couldn't find the right thing to say. He later confided to Cristina that he felt he could not talk with his siblings about it because he had already mourned Livvy's death in the hunt, and that his grief was different.
Shortly after the funerals, Julian, Emma, and Diana were called to Jia's office where she informed them Horace Dearborn, as the new Inquisitor, planned to interrogate Mark, Helen, and any other Downworlders (or part Downworlders) who were in Alicante. She told them Magnus and Alec were planning on Portalling out that night and recommended that do the same. At the Institute Mark noticed Helen was having a hard time connecting with the younger siblings. He comforted her, offered her advice, and reassured her that it had been the same way for him at first but that they would come around.
Mark went with Cristina to investigate some ley lines Catarina Loss thought may be corrupted. While there he and Cristina were attacked by a horde of Harpyia demons. Though they fought them off well, there were too many of them and they tried to flee but failed. Luckily Kieran saw them on his way to the LA Institute on the back of Windspear and quickly helped them onto the back of the steed to escape. Once back at the Institute, Kieran told him that he had heard the Cohort at the Scholomance talking about Julian and Emma being on a suicide mission in Faerie. The trio immediately began making plans to go to Faerie to rescue them. Cristina reached out to Jaime Rosales and once he arrived with the Eternidad, they left for Bram's Crossroads.
The landed in Faerie in the middle of Prince Oban's revel and learned they had missed the Queen's procession that Julian and Emma were a part of. In a fit of rage, Mark grabbed a drink from Tom Tildrum, assuming it was just fruit juice like last time, and passed out. Kieran and Cristina then carried him to a clearing by the road where they hoped they'd be safe. Mark awoke to see Kieran and Cristina sharing a kiss but before he could say much, they were surrounded by Manuel Villalobos and Oban's guards. Though he and Kieran were captured, Cristina was able to escape to get help.
Oban and Manuel decided to bring them to the King in hopes of exchanging them for the deaths of some other prisoners. Chained to Oban's saddle, they were forced to walk the path of punishment where they were meant to be berated and abused but no blows came. Astonished, Mark heard the fey along the path exchange stories of Kieran's kindness and their distaste for the King. Afterwards they were brought before the King in the Unseelie Tower. To his shock, Cristina, Emma, Julian, Jace, and Clary were marched in by Adaon not long after. A fight soon broke out and once he was free from his chains he escaped with Cristina and the others using the Eternidad, but not before Kieran killed the King.
When they appeared at the Institute, Julian and Emma appeared separately only moments after, but clearly having been some where else as they had arrived in strange clothes, badly injured, and unconscious. Mark stayed with Julian, keeping an eye on him until he woke up 3 days later. He and Emma told them the story of a land called Thule and all they had learned there that could help them now and the group began talking strategy.
The following night, while patrolling the perimeter, he and Kieran began to discuss Faerie and Kieran expressed how he feared no one was looking out for his land in the plans they had discussed. Mark suggested that he should do so, as King and later that night Gwyn suggested the same, though Kieran had refused them both. Upon Cristina's arrival, Kieran announced that he loved and desired them both, and would like to be with the both of them. Mark was appalled, assuming that as she was not fey she would be repulsed by such a suggestion, but she surprised him saying only that she feared they would both leave her. Mark assured her they would not and they all began embracing and kissing one another. In their newfound relationship, Mark and Cristina did their best to support Kieran as he realized that he would have to become king and ensure him that he would make a great one.
Julian soon held a war council and created a resistance against the Cohort—which he had named Livia's Watch—that would interrupt the upcoming parley and confront them. Mark was among the first group to approach the Imperishable Fields and had started antagonizing Oban by calling him "prince", not "king", which others soon followed suit. During this confrontation, Kieran challenged Oban for the throne via a battle to death, which surprised Mark. As battle ensued, Mark and Cristina fought their way to help Kieran. Mark called on Gwyn to distract some of the redcaps attacking Kieran by going after Oban. Mark managed to make it to his side and he and Kieran fought Winter together until Cristina killed Oban. At which time she and Mark began calling that Kieran was now the King, and Winter and the others had begun to kneel to him.
However the battle was not over. The Cohort was still fighting, some of the fey were confused and still attacking, and the Riders had shown up and were not listening to Kieran's orders. Mark found himself losing in battle with Eochaid but soon Cristina, Julian, Kieran, Winter, and even Diego had shown up to help, though of course that meant more Riders had come as well. They battled fiercely till Hypatia Vex appeared and used her magic to sweep all the Riders across the field for a temporary breather. Mark and Cristina were the first to notice Julian and Emma rise up as True Nephilim—becoming giants imbued with Heavenly fire. Under Dru's suggestion, against the warnings of others, all the siblings marched to put themselves before them and managed to talk them down.
A few days after the battle Kieran revealed that he had to return to Faerie for good. That as king he could not be away from the land for long and he could have no mortal consorts. Mark and Cristina were devastated that they would no longer be able to see him but took comfort in at least having one another. Still, Cristina was determined to find a way the could all still be together and her and Mark reached out to Adaon for his cottage—as it existed on land that was neither fey nor mortal, they hoped it existed outside the laws. Adaon did not respond and waited some time to offer it to Kieran. Though once he did, Kieran flew to join them on the beach, where they were celebrating Magnus and Alec Lightwood's wedding.
With the Clave in exile and Alec now the Consul, Alec approached Mark and asked him if he would take his place in helping head up the Downworlder-Shadowhunter Alliance and be an ambassador to the fey. He also extended the offer to Cristina considering her knowledge on and her families relationship with the fey. Though this was what Mark had wished for—a way to make a difference in both parts of his world—he was apprehensive about leaving his family and moving to New York. Julian convinced him to take it and he and Cristina both headed there to be a part of the alliance.
Mark is tall, thin, has broad shoulders, and bore the signature blue-green eyes of the Blackthorns. However, since Mark became part of the Wild Hunt; his right eye has since turned gold. Like Helen, he also has pointed ears and pale white-gold hair that curls in ringlets. As they both share their mother's faerie blood, both have a rather delicate bone structure.
Mark has scars on his back from being whipped and beaten during his time in the Wild Hunt, and from a time when runes were carved into his skin with knives.
While Mark was gone for five mortal years, time moved differently in Faerie and so Mark aged differently. Mark appears around three years younger than he really is, looking about the same age as Julian.
Mark is quite serious and somber, having been alive for much longer than his age would suggest, and having been through a lot of trauma for someone his age. Also, because of the time he has spent away from humans and among faeries, Mark no longer easily catches onto sarcasm or humor.
When he was younger, Mark was impatient and easily annoyed; like a typical teenager, he believed himself more mature and above his younger siblings. Nonetheless, he loved and cared for them deeply.
Mark also enjoys reading.
Skills and abilities
- Nephilim physiology: Being Nephilim, Mark possesses a variety of enhanced physical and mental abilities granted to him by the blood of Raziel in his veins and also by the angelic Marks of the Gray Book. He also has the power to perform tasks unique to their species, such as the ability to use and call on the power of the angels for their seraph blades. This includes enhanced strength, agility, stamina, and coordination, which only improves over time and practice.
- Runic magic: Due to the angel blood in their veins, all Shadowhunters are able to apply runes on their skin without any real danger. These Marks, in turn, give varied effects that serve to benefit the wearer.
- Use of heavenly weapons: As a Shadowhunter, Mark is also able to perform tasks unique to their species, such as the ability to use and call on the power of angels for their seraph blades, as well as to handle any heavenly weapons or objects with effect, which would normally not work for other species. In particular, these are tools made of adamas and forged by Iron Sisters.
- The Sight: As a Shadowhunter and half-faerie, Mark is naturally and easily able to see through most magical illusions and layers of glamour over reality.
- Enhanced hearing: Because of his faerie blood, Mark has a better sense of hearing than others, though not as much as that of a pure faerie, his would compare when aided by Shadowhunter runes.
- Immunity to fey weaknesses: Though he is part-faerie, things that affect and weaken other fey do not harm him, such as his faerie name, rowan wood, and pure iron, though the latter two may bother him.
- Accelerated healing: Mark and all Hunters are protected by magic that significantly hastens their healing process, though this does not enable them to recover as fast as a Shadowhunter's iratze would, and wounds do not fully heal and may leave more scars than when an iratze is used.
- Sensing: Due to his years of training among faeries, Mark is able to sense certain elements, such as ley lines and convergences.
- Marksmanship: Mark is a master at archery and is a spectacular marksman, owed to his years of experience as a Hunter.
- Stealth: The Wild Hunt and living with faeries has trained Mark to be incredibly graceful, enabling him to make little to no sound when moving. With this ability, Mark often frightens people and catches them off guard as they don't hear his approach.
- Faerie steed: Mark's brown Faerie steed while with the Hunt; its magical substance and nature allowed it to change its form from a horse to anything that would fit any world—such as a motorcycle, that could still fly, in the mundane world. It was destroyed by a Mantid demon.
- Bows and arrows: As a member of the Wild Hunt, Mark primarily used bows and arrows.
- Elf-bolt: Given one by Kieran, Mark was skilled and able to master the use of the deadly, poisonous faerie weapon. It became his favorite weapon. Mark used to wear its tip on a chain around his neck, though he eventually returned it to Kieran.
|“||Kieran had spoken with Mark and listened to him; one did not realize how much one lost when no one spoke to you as if you were a person with worthwhile things to say until enough time had passed that the desperation was so intense you would begin to talk to rocks and trees. Kieran had given Mark back his humanity through the grace of ordinary affection and now Mark did not know how he would live without it.||”|
Kieran and Mark met in the Wild Hunt. Both found solace in each other as both were ostracized in the Hunt. When riding together, Kieran made their trips fun, showing Mark wonders that only the Fair Folk knew of. Eventually, they fell in love and Kieran gave Mark his first kiss, as well as an elfbolt as a gift. Kieran was the only member of the Hunt that Mark could confide in and say that he was still a Shadowhunter.
When Mark was returned to the Blackthorns, Kieran kept an eye on him. When Kieran, under the belief that he would be saving Mark from a lie Iarlath told him, accidentally got his brother Julian and his friend Emma in trouble, Mark furiously broke off their relationship. However, this did not stop Kieran from helping the Blackthorns in their time of need after.
When Kieran was to be executed at the Unseelie Court, Mark saved him, and when they realized that Kieran had no recollection of his betrayal or their break up but needed him to cooperate with them, Mark played a part to continue a semblance of their relationship. His distance from Kieran did not go unnoticed by him, and Kieran was bitter about being used once his memories were returned to him. With Cristina's help, Kieran listened to Mark then told him that after paying his debt to Mark's family, they would be done.
Soon though Kieran confessed that he could not be done with Mark and Mark agreed. They then continued their relationship with the addition of Cristina Rosales—whom both had come to love.
|“||I meant it when I said you are beautiful. I want you.||”|
When Mark first returned to the Institute, Cristina was the only person he felt comfortable being around as she was the only one who, having no prior connection with him before, would have no expectations of him. Cristina helped him feel more comfortable at the Institute and around his family, even cutting his hair to make him look more like a Shadowhunter.
When Cristina's ex-boyfriend Diego appeared, Mark showed some signs of jealousy. When he needed to talk with Cristina believing she would be the only one able to understand his feelings, he walked in on her and Diego kissing and left, feeling devastated, thinking he had gotten the wrong idea about them.
Mark's feelings for her, and vice versa, further developed romantically, more so when they became free to act on their feelings upon his breakup with Kieran and that of Cristina and Diego's, further established by their time and ordeals together.
Things quickly grew complicated after they rescued Kieran and realized Kieran had no memory of their breakup. Eventually the trio came to realize they all loved one another and wanted to be together so they began a poly-amorous relationship.
|“||You showed me how to be apart of a family again.||”|
Julian is Mark's younger brother. As children, Mark and Jules acted like most siblings did: they fought and bickered and found each other annoying, but they cared for one another. According to Emma, they used to have really vicious fights when they were younger. When they were separated, Mark became thoroughly concerned about Julian's and their other siblings' well-being. Upon reuniting with them after a long time, Mark felt that he no longer knew Jules, who had changed so much since they last saw each other, and they occasionally clashed about certain decisions. Nonetheless, Mark was proud of him for being able to hold their family together by himself.
|“||There is nothing wrong with Ty, but he is different, and the Clave hates all that is different. They will try to punish him, for being who he is. They would punish a star for burning.||”|
Ty is Mark's younger brother. They got along well and had fun together. Mark is even one of the few people who manages to get through to Ty during his bad moods. When Mark put butter on his microscope, Ty, who is ultra-careful about his belongings, seemed to be amused. When Julian told Mark that he needed to act more normal in public, Ty defended Mark. For a while, Mark did not realize the gravity of Ty's expectation in him, but when he did, Mark felt pressured and overwhelmed.
Helen is Mark's older sister. Mark always felt a special connection to Helen, since they are both half-faerie. When they were reunited following Helen's exile and Mark's return for the first time in five years, Mark embraced her in a big hug and they made plans to talk later that evening.  When Helen was having issues with connecting with her siblings after Livvy's death, Mark comforted her and told her he went through the exact same thing when he returned home. 
Mark and Emma became closer after his return from the Wild Hunt, owing to both's maturity and shared responsibilities, compared to prior the Dark War with their four-year age gap. For a time, Emma asked Mark to pretend and let the others believe that they were dating. Mark asked if they could make it real and kissed her but stopped when Emma began crying. Instead, Mark agreed to her request, unaware of the real reason, and grew even closer to Emma during this time, sharing many bonding moments during the nights when they slept at each other's rooms.
- The Last Stand of the New York Institute (mentioned only)
- The Red Scrolls of Magic (mentioned only)
- City of Lost Souls (first alluded to)
- City of Heavenly Fire (first appearance)
- Pale Kings and Princes (mentioned only)
- Bitter of Tongue
- The Fiery Trial (mentioned only)
- The Land I Lost (mentioned only)
- Lady Midnight
- Lord of Shadows
- Queen of Air and Darkness
- The Lost World
- See more here
His full name is Mark Antony Blackthorn, following the Blackthorn tradition, wherein their names are of Greek and Latin origin. He was named after the Roman Mark Antony, the lover of Cleopatra and a loyal friend to Julius Caesar, whom his brother Julian is named after.
- Like his sister and most other faeries, Mark is bisexual.
- Mark used to love coffee before his stay with the Wild Hunt; now, he is repulsed by it.
- Mark's true age, including the time he spent in Faerie with Helen and Nerissa and with the time he spent with the Wild Hunt, is unknown. Their starting age since joining the human world was a guesstimate by Andrew, who made up their designated birthdays for celebration purposes.
- Mark is an expert in throwing knives and daggers. He is also skilled in the long sword and whip.
- Mark is not much of a cook but he invented a doughnut sandwich—a doughnut cut in half with jelly, peanut butter, and honey in the middle—that his family came to enjoy and request of him.
- Mark briefly owned a goldfish that he named after the warlock, Magnus Bane.
- ↑ 1.0 1.1 City of Heavenly Fire
- ↑ 2.0 2.1 An Illustrated History of Notable Shadowhunters & Denizens of Downworld
- ↑ 3.0 3.1 3.2 3.3 3.4 Lady Midnight
- ↑ Bitter of Tongue
- ↑ 5.0 5.1 5.2 5.3 5.4 5.5 5.6 Lord of Shadows
- ↑ 6.0 6.1 6.2 6.3 Queen of Air and Darkness
- ↑ Blackthorn names — Cassandra Clare on Tumblr
- ↑ "Just faeries." Cassandra Clare on Twitter
- ↑ "So what we know of their ages is a guesstimate," Cassandra Clare on Tumblr
- ↑ "The Blackthorns and friends" — Cassandra Clare on Tumblr