Jesse grew to be a weak and sickly child, incapable of being trained to be a warrior, to the point where his mother even begged to not have him marked with runes when he was a child, though he survived this painfully. When he was sixteen, Tatiana was finally told that he could no longer live and soon succumbed to his illness.
- The Midnight Heir (first mention)
- The Last Hours (will appear)
- Lady Midnight (mentioned only)
- Lord of Shadows (alluded to)
- Though Jesse died before he could be fully runed, he has a scar on his hand from a Voyance rune.
- In The Midnight Heir, Jesse apparently died when he was 16 due to sickness. It is implied that his mother is planning to use dark magic and sacrifice five Shadowhunters to revive him, which would explain why the "found" family tree states that Jesse died at the age of 59.
- The mystery of Jesse's state boggles the writers' mind of Lucie Herondale.
- Jesse may at first return as a ghost after his death, furious that he missed out on life and seen only by Tatiana, Grace, and Lucie.
- According to the found family tree, Jesse apparently went on to marry Lucie and had children with her.
- This mystery is expected to be explored in The Last Hours, as he is also set to be a main character in the upcoming trilogy.
- Jesse is set to be a pianist.
- ↑ "...and has been since 1896" - Cassandra Clare on Tumblr
- ↑ The Midnight Heir
- ↑ 3.0 3.1 "... and Jesse) are the main characters in the book." Cassandra Clare on Tumblr
- ↑ "...he does have a Voyance scar on his hand" — Cassandra Clare on Tumblr
- ↑ "A mystery that occupies the busy brain of writer [Lucie Herondale]", Cassandra Clare on Tumblr
- ↑ "Ah, the enigma that is Jesse Blackthorn!" Cassandra Clare on Tumblr
- ↑ "Jesse Blackthorn used to play the piano when he was alive." Cassandra Clare on Tumblr