At some point, Horace's wife died, and he was left to raise Zara to share his hateful views on Downworlders and follow in his footsteps. After the Cold Peace was established, Horace gathered a group of radical Shadowhunters who shared his views and together started the Cohort, establishing himself as the unofficial leader.
In 2012, Horace kept track of his daughter's progress at the Los Angeles Institute by trading letters with her. The pair intended to take over the Institute, with the ulterior motive of pushing his proposal for the Registry further. He later attended the Council meeting where Annabel Blackthorn was to testify and spoke out against her and the Blackthorns, taking part in the heckling of Annabel by the Cohort members.
Horace is a very ambitious and conniving man. He hates Downworlders and any who associate with them, including Shadowhunters like Mark Blackthorn who have Downworlder blood.
Horace is a brown-haired man with an expressionless face.
- Lord of Shadows (first appearance)