A parabatai is a pair of Nephilim warriors who fight together as lifelong partners, bound together by oath, regardless of their gender. Their bond is not reflected only in their closeness and willingness to lay down their lives for one another, but also in oath—one sworn in front of the Council.
Not all Shadowhunters are required to have parabatai; it is actually less common to have them. A Shadowhunter has only eighteen years to find and choose a parabatai; once older than that, the ritual is no longer open to the Shadowhunter.
Today, parabatai must be bonded in childhood; that is, before either has turned nineteen years old. They are not merely warriors who fight together; the oaths that newly made parabatai take in front of the Council include vows to lay down one's life for the other, to travel where the other travels, and indeed, to be buried in the same place.
Trial of water
Prospective parabatai must undergo some tests before their ceremony to make sure their bond is true; the trial of water is one such test. The test itself is kept secret and must be done without prior knowledge to it being taken—knowing ahead of time and preparing can tamper the results.
The pair consume water from Lake Lyn, typically distilled and served as tea. The waters of the lake will cause them to hallucinate. The objective is to see if they both go to the same place in their mind and, when put to the test in this hallucination, that they both risk their own lives to save the other, defying the point of where they should die in order to rescue one another. Passing the test proves the existing link between them before the bond makes it official.
Trial of fire
In the actual ceremony held to bind the parabatai—referred to in name as "the Fiery Trial"—there will be three rings of fire on the ground: two for the individuals, and a third one in the middle that will serve as the shared ring, seemingly symbolizing the union or joining of the pair as parabatai. The words of the parabatai oath are spoken, and parabatai runes are exchanged and placed on each other.
The first two male Shadowhunters Jonathan and David fought side by side as the first parabatai. Tradition tells that the ritual they performed was quite different from the current one: they took each other's blood, spoke the words of the oath, and inscribed the runes of binding upon each other.
Entreat me not to leave thee,
Or return from following after thee—
For whither thou goest, I will go,
And where thou lodgest, I will lodge.
Thy people shall be my people, and thy God my God.
Where thou diest, will I die, and there will I be buried.
The Angel do so to me, and more also,
If aught but death part thee and me.
Two witnesses are required for the ritual, though their presence is mostly symbolic. Their responsibility is similar to that of suggenes and are typically two people of importance to those being bonded. During the ceremony, each stands on the wing of the angel depicted on the floor, near to the person who chose them's ring of fire.
- Will Herondale and Henry Branwell for James Herondale and Matthew Fairchild (respectively)
- Clary Fairchild and Simon Lewis for Emma Carstairs and Julian Blackthorn (respectively)
A Shadowhunter may choose only one parabatai in their lifetime and cannot perform the ritual more than once. Most Shadowhunters never have any parabatai at all; so, being fortunate enough to find someone worthy of becoming ones' parabatai is considered a blessing. This ritual bond enhances the natural feelings of love and friendship that already exist between the pair; however, this does not prevent rivalry or hate from forming between them.
The parabatai runes placed upon them enable them to draw on each other's strength in battle. They also maintain a strong connection between one another and are able to sense each other's life force; Shadowhunters who have lost their parabatai describe being able to feel the life leave their partner, and when something supernatural happens to the other. In addition, Marks made by one parabatai upon another are stronger than Marks drawn by others, and there are Marks that only parabatai can use, because they draw on the partners' doubled strength.
Like the marriage bond, the parabatai bond is broken, normally, only by the death of one of the members of the partnership. However, the binding can also be cut, or may fade, in some rare circumstances: if one becomes a Downworlder, if one leaves their life as a Shadowhunter to be with a mundane, or if one is stripped of their Marks and becomes a mundane, and if one is exiled, its enchantments and formal ceremony lessening ones' Nephilim magic, gradually weakening the bond.
When one becomes a Silent Brother or an Iron Sister, the bond dissolves naturally as the Marks of transformation that new oblates take are among the most powerful that exist and overwhelm and dissolve the parabatai Marks of binding just as they overwhelm and dissolve more ordinary warrior's Marks.
Additionally, when the bond is severed or twisted in any way, when they are separated or if a great distance is placed between them, the partners would feel the connection break, or could feel constant or sudden painful sensations comparable to literal tugs to their hearts, or some other strange feeling easily associated with it.
The only bond forbidden to the parabatai is the romantic bond, and it has become a rule upheld by the Clave, written into the Law and the Shadowhunter's Codex, and embedded into the beliefs of many generations of the Nephilim. The Shadowhunter-troubadours' in the late Middle Ages made several songs depicting the forbidden love of parabatai pairs and the inescapable tragedies, both of heartache and magical disaster, that befell them when they become romantically linked.
However, the real reason it was written into the Law, aside from the symbolic and practical reasons, was kept a secret from most Nephilim and had been considered a long-hidden mystery. Very few people know the reason why love between parabatai is forbidden, and records of it have either been lost, destroyed or hidden deep in the archives of the Silent City and the Spiral Labyrinth, shrouding the truth in secrecy.
True love between parabatai will strengthen their power to the point of magic. The more the pair surrenders to their emotions and love for one another, the stronger the curse gets and affects them. At first, the pair will have increased power with runes they apply on one another, more so than typical parabatai that even fatal wounds are healed with their iratze, and they will have the ability to do things no other Nephilim could do, such as when Emma Carstairs destroyed the Mortal Sword with Cortana.
Eventually, their runes will begin to burn with heavenly fire, and black lines will spread on their skin until, finally, they turn into enormous beings—true Nephilim. Because both are transformed—instead of the proper circumstance when one of the pairing should remain untransformed to anchor the other to Earth—the parabatai will have little control or conscious acts while in this form. This may cause the pair to lose complete control and kill others around them until they die themselves, burned by their heavenly fire. When they somehow survive, however, they may awaken with their parabatai rune and bond broken.
|“||And it came to pass... that the soul of Jonathan was knit with the soul of David, and Jonathan loved him as his own soul... Then Jonathan and David made a covenant, because he loved him as his own soul.||”|
–1 Samuel 18:1–3, The Shadowhunter's Codex
The idea of parabatai bonds came from an old tale, particularly the biblical tale of David and Jonathan, warriors who loved each other dearly and whose souls were knit together by Heaven after forming a covenant. Out of that story, Jonathan Shadowhunter and his companion David, who were coincidental namesakes of the biblical characters of the same name, took the idea of parabatai, created the rune and ritual for it, and encoded the ceremony into the Law.
Because Shadowhunters aren't meant to wield magic, and because the rune and ceremony was created by man and not by Heaven, the rune has a dangerous corruption: the aforementioned curse. It also has a weakness: The first parabatai rune ever inscribed by Jonathan and David with their blood on a stone tablet is kept in the room of the Speaking Stars in the Silent City. If it is destroyed with the Mortal Sword, all the parabatai runes and bonds in the world will break.
During the time of the rune's conception, giant demons still ravaged the earth, and in response, Shadowhunters transformed into true Nephilim, marking an ultimate sacrifice as most would die in a blaze of heavenly fire afterwards. Those with parabatai, however, often survived the transformation when their parabatai did not transform and kept them anchored.
There are at least two known incidents of a pair of parabatai lovers who both transformed, uncontrollably, into true Nephilim and wreaked havoc, murdering their families and anyone who got in their way, before being burned alive by their heavenly fire. In another, a pair of Shadowhunters became powerful magicians, comparable to warlocks, and razed a town to the ground. Because of these incidents, the Law against parabatai being in love was implemented. To prevent others from potentially taking advantage of the power, the reasons and history behind the Law were covered up and kept secret for generations since, but the practice was not ended as it was valued as one of the most powerful tools of Shadowhunters.
Eventually, giant demons stopped coming to earth, and Shadowhunters turning into true Nephilim, but parabatai who fell in love, despite the Law, risked turning into true Nephilim unnecessarily.
- Jonathan Shadowhunter and David the Silent (split by David's Silent Brotherhood)
- Amicia of Poitiers and Gundred of Meissen
- Silas Pangborn and Eloisa Ravenscar (split by Silas' death)
- Jem Carstairs and Will Herondale (split by Jem's Silent Brotherhood and Will's death)
- James Herondale and Matthew Fairchild
- Cordelia Carstairs and Lucie Herondale
- Michael Wayland and Robert Lightwood (split by Robert's exile and Michael's death)
- Valentine Morgenstern and Lucian Graymark (split by Luke's Downworld transformation)
- Jace Herondale and Alec Lightwood
- Edward Longford and his unnamed parabatai (split by the latter's Turn into an Endarkened)
- Julian Blackthorn and Emma Carstairs (split by heavenly fire when they turned into true Nephilim)
- Julie Beauvale and Beatriz Mendoza (split by Julie's death)
- Clary Fairchild and Simon Lovelace
The use of the Shadowhunter term parabatai comes from heniochoi kai parabatai which means "charioteers and side-men" in Ancient Greek, where the side-man (the parabatai) cannot leave the charioteer (heniochoi) and fights from the chariot to protect the other, while the charioteer drives; the one is useless without the other. In other terms, it can also mean a soldier paired with a chariot driver.
The usage heniochoi kai parabatai is derived from the words heníochoi ("hνίοχοι", or êniochoi), which translates to "charioteers", and paraibatai ("παραβάτης", or parabatés), which means "chariot-fighters", companions, or "a warrior beside the charioteer, or a certain type of foot-soldier". It originates from the Greek units that fought in pairs. In Iliad, Dionysius of Halicarnassus said that poets called parabatai the Athenians' apobatai—sidemen in chariots which were a crucial element of the Panathenaic procession. The partnership of the heniochoi and parabatai is more popularly referenced from the Sacred Band of Thebes, where the partners (the typically older heniochoi and the younger parabatai) were male lovers, with the idea that, according to Plutarch's Life of Pelopidas and Plato's Symposium, soldiers in said "army of lovers" would fight more fiercely—"willing to rush into danger for the relief of one another"—and more cohesively when alongside a lover or with someone they are bonded to. The Greek word parabatai can also translate to "violator, transgressor", or "the one who sins".
- All parabatai bonds are different. Some may experience it on a physical level while others' are more emotional or intuitive.
- Witnessing the ceremony of another set of parabatai can cause a powerful reaction in true parabatais.
- The second pair of parabatai were Amicia of Poitiers and Gundred of Meissen. They are known for having teamed up against a Dragonidae infestation in Teutoburg Forest. When they died, a monument to them was made in Idris.
- A demonic twinning spell that binds two people has been compared to and referred to as a darker form of the parabatai bond, wherein one individual is superior to the other and is capable of impressing upon the other member their thoughts and feelings. When one is injured, the other is as well, and when one dies, both die. Since this robs one member of the bond of their free will, it is considered the demonic equivalent of the bond.
- The words of the parabatai oath is a variation of the verse Ruth 1:16-17 from the Bible: "Don't urge me to leave you or to turn back from you. Where you go I will go, and where you stay I will stay. Your people will be my people and your God my God. Where you die I will die, and there I will be buried. May the Lord deal with me, be it ever so severely, if even death separates you and me."
- The Fiery Trial
- Parabatai ceremony — Cassandra Clare on Tumblr, with art by Cassandra Jean
- The Shadowhunter's Codex
- The City of Bones, a Chain of Gold extra
- "Or does their bond prevent such situations?" — Q&A with Cassandra Clare on Tumblr
- "Parabatai (again!)" — Cassandra Clare on Tumblr
- Clockwork Princess
- Lord of Shadows
- City of Lost Souls
- Lady Midnight
- The Mortal Instruments
- Clockwork Prince
- Queen of Air and Darkness
- Shadowhunter Army June 2020 Newsletter
- "parabatai" 1 — Cassandra Clare on Tumblr
- Clockwork Angel
- James, Sacra Pagina #14
- Homer's People: Epic Poetry and Social Formation by Johannes Haubold
- The Peloponnesian War: A Military Study by J.F Lazenby
- Hoplites: The Classical Greek Battle Experience by Victor Davis Hanson
- Sacred Band of Thebes — Hellenica, Michael Lahanas
- Sacred Band of Thebes — AbsoluteAstronomy.com
- Sacred Band of Thebes on Wikipedia.org
- An older version of the "Sacred Band of Thebes" Wikipedia entry
- Various Bible-based disctionaries: 
- "All parabatai bonds are different." Cassandra Clare on Tumblr