Eva Blackthorn was a Shadowhunter and the beloved wife Tobias Herondale. She was executed by the Clave in the place of her missing husband as punishment for his crime of deserting fellow Shadowhunters in battle.
Eva's apparently surprising marriage to Tobias bore fruit when she became pregnant with their first child.
Months into her pregnancy, Eva fell ill and Tobias was called to battle at Bavaria. During the battle, Tobias was deceived by a warlock into thinking that Eva was in danger; the illusions, in fact visions of the future that would not have come to pass if he was able to fight the trickery, broke Tobias's mind. Believed to have fled and abandoned his companions in fear, Tobias was set to be punished for what the Clave saw as an extreme crime had he been found. Since he went mad and never managed to return, Eva and their unborn child's lives were forfeit instead.
Catarina Loss, who at the time knew the family well, used magic to sneak into her prison in the Gard, make her go through labor and give birth to their son early, and make it look like she was still carrying the child afterwards. Eva kept this secret to the grave, and the Clave never suspected a thing.
Eva was, according to Catarina, a strong, brave woman; a "raven-haired spitfire"—apparently somewhat like present-day Isabelle Lightwood. She was quite the opposite of her mild husband, resulting in quite the unexpected match.
Eva is a female given name derived from a Hebrew name meaning "life" or "living one". It can also mean "full of Life" or "mother of life". It is the Latinate counterpart of English Eve.