|“||Abigail Shadowhunter set the precedent for Shadowhunters comprising both men and women, a guiding principle that has continued to this day.||”|
On the trip that changed their lives, Abigail was on her way to Constantinople during the Crusades, with her two companions Jonathan and David, to join and marry her fiancé, whom Jonathan was said to be unhappy about.
According to the Shadowhunter's Codex, the three of them were attacked by a demon that wounded Jonathan, making them realize the gravity of their situation with the demons' arrival. A few days after the initial encounter, they wound up at the Lake Lyn. There, they were attacked, and soon overpowered, by a swarm of demons. They were being drowned by the demons at the lake when the Angel Raziel was believed to have arrived, heeding Jonathan's prayer. The angel rescued them from the lake, and Jonathan immediately set to work on nursing Abigail and David back to health and having them drink from the Mortal Cup, making them the first Shadowhunters.
In her time as a Shadowhunter, Abigail demonstrated that the female Shadowhunters were no less fierce and resolute than the Shadowhunter men. When she grew older, no longer physically able, she decided to study the adamas, with help from the Gray Book, making her the first Iron Sister. Along with six other Shadowhunters, she constructed the first adamas forge, which was the earliest incarnation of the Adamant Citadel. When the Citadel was eventually built, it was decided that it would only be open to female Shadowhunters, as protection from unwanted interference by male Shadowhunters.
- The Shadowhunter's Codex (first and only appearance)