Alastair did not get along well with his younger cousins, or at least made no effort to get to know them. When James Herondale first attended the Shadowhunter Academy in 1899, Will had hoped that they would be friends; instead, Alastair and his friends immediately began terrorizing him and other family friends that were also new students: Matthew Fairchild, Christopher and Thomas Lightwood. Alastair mostly bullied James, pointing out his odd, yellow eyes and giving him the nickname "Goatface Herondale" that stuck with the boy for weeks.
After James's ability to Change into a shadow was revealed to the whole school, Alastair and his friends decided to play a prank on him. During one of the training missions in the Brocelind Forest, they placed a bigger rogue Vetis demon into the Pyxis that was only supposed to contain a small, harmless demon. The prank went horribly wrong, however, when his friend Clive Cartwright was killed by the demon. Alastair and their other friend freaked out and hid but was pursued by James in his shadow form, who then threatened Alastair with a sword. James then scared the pair enough to make them flee.
Afterwards, James was expelled for their misdoing. Alastair approached James as he was about to leave the Academy and apologized. On the other hand, Matthew Fairchild, James's friend who had been with him when they saw Clive's corpse, enacted his revenge by placing all his belongings in the south wing, which Matthew and the others had just rigged with explosives.
- Nothing but Shadows (first appearance)
- A History of Notable Shadowhunters & Denizens of the Downworld
- The Last Hours (will appear)
- Alastair reads mundane newspapers to find hints of demonic activity.
- He does not get along well with his sister, Cordelia, who finds him annoying.
- During their childhood, they shared a common interest in architecture. Inspired by their last name, the two collaborated to build castles out of wooden blocks.
- Cordelia loved scaring him when they were younger, specifically by grabbing his ankle while hidden under his bed, resulting in an ongoing habit of Alastair's to look under beds before getting within an arm's length of them.
- He dyes his hair blond.
- According to a found family tree, Alastair died in 1928 at the age of 43 or 44. Also according to the family tree, he is the direct ancestor of John and Emma Carstairs. His name on the tree was spelled "Alistair".
- Alastair shares a name with Alastair Hunt, a character from Cassandra Clare's The Magisterium series.
- ↑ "Her kids are biracial and were born in what was then Persia." Cassandra Clare on Tumblr
- ↑ 2.0 2.1 "Found" family tree, a Clockwork Princess extra
- ↑ The Last Hours character portraits and details — Cassandra Clare on Tumblr
- ↑ 4.0 4.1 Nothing but Shadows
- ↑ "She doesn't get along with her brother." Cassandra Clare on Twitter
- ↑ "Because he's annoying." Cassandra Clare on Twitter
- ↑ 7.0 7.1 A History of Notable Shadowhunters & Denizens of the Downworld
- ↑ "He dyes his hair", Cassandra Clare on Twitter