Jesse was a weak and sickly child growing up. Because of that, Tatiana told the Silent Brothers he could not be Marked. However Jesse desperately wished to be a Shadowhunter like all the others so he contunually begged and pleases with his mother to let him be runed. Finally, when he was 17, she relented after he threatened to run away to Alicante and have them done himself if she did not let him.
The rune ceremony went well at first, but when he returned to his room, he collapsed. He woke up with a fever and screaming, blood welling from his skin. His adoptive sister Grace stayed with him and even held him in his final moments. Just as he realized he was dying, his mother came in and held the Blackthorn locket to his lips to capture his last breath.
After his death, Tatiana refused to give the Silent Brothers his body. Instead she brought a warlock into the room in the hours following to preserve and safeguard his body. His soul was then cut from it, making him free to wander both the real world and the spirit world; though he is not able to crossover. For some reason, Jesse's spirit is only conscious during nights and is strong enough that he is able to lift and touch people.
Over the years, Jesse spent his nights wandering in Brocelind Forest or reading books or his grandfather's papers. One night in 1897, while wandering the forest, he came across a small girl who had fallen into a faerie trap. He was surprised when she saw him as prior to that night, no one had been able to see him aside from his family. He was even more surprised by his ability to lift her out of the hole. Jesse attributed this to her youth.
In 1903, seven years after his death, his mother was still trying to find a way to resurrect him. She called for Magnus Bane requesting that he kill five Shadowhunters for her in order to accomplish this task; a job Magnus refused to do. Despite this set back, Tatiana still hoped that once she has all the ingredients a warlock would need, his last breath could be used to bring him back.
Later that year, Jesse re-encountered the girl from the forest at a party in the London Institute. When he realized she could still see him, he dragged her away from the party and explained to her who he was. He and Lucie met and talked many times after this, the two became close and Jesse began confiding in her, even asking for her help when he believed his sister to be in trouble. And when her brother was dying, Jesse gave his last breath to James Herondale in order to save his life.
Though he was able to stay a ghost, he lost his strength to be a solid entity that could be touched. He and Grace, having realized the extent of their mother's madness through the reveal of her deals with demons, decided they could no longer trust her and made plans to get her the help she needed. While Lucie was visiting his grave, he thanked her for allowing him to be a hero but asked that she not try to save him.
Jesse has straight black hair and eerie green eyes. He is tall like his mother, slender and shockingly pale skin, and has a lovely melancholy face with the handsome, angular features like his uncle, Gabriel.
In his ghost form, he is always dressed in white shirtsleeves and black trousers. He has a scar on his right hand from his Voyance rune. Jesse also wears a silver Blackthorn ring on his right hand and a gold locket with a circle of thorns etched on its surface.
- The Midnight Heir (first mention)
- Chain of Gold (first appearance)
- Lady Midnight (mentioned only)
- Lord of Shadows (alluded to)
- See more here
- Jesse's weapon of choice is the Blackthorn sword.
- In The Midnight Heir, Jesse apparently died when he was 16 due to sickness, years after his supposed rune ceremony. This may be a continuity error or simply Tatiana lying as she often does.
- A "found" family tree states that Jesse died at the age of 59. This may be because of his mother's plans to resurrect him.
- Also according to the found family tree, Jesse apparently went on to marry Lucie and had children with her.
- Jesse is set to be a pianist.
- He doesn't know much about his father as Tatiana has created a whole false narrative of her life.
- Jesse's favorite book is A History of Notable Shadowhunters.
- His favorite animal is the red fox.
- ↑ "...and has been since 1896" - Cassandra Clare on Tumblr
- ↑ 2.0 2.1 2.2 2.3 Jesse Character Card — Cassandra Clare on Instagram
- ↑ 3.0 3.1 3.2 3.3 Chain of Gold
- ↑ 4.0 4.1 The Midnight Heir
- ↑ "Jesse Blackthorn used to play the piano when he was alive." Cassandra Clare on Tumblr
- ↑ "...the information he’s gotten hasn’t been very solid." CC on Tumblr