Daniel Gilpatrick was an Irish Torontonian. He had a daughter called Margaret Gilpatrick.
When Margaret joined the Irish Republican Brotherhood her behaviour changed so much that Gilpatrick believed his daughter had been kidnapped by faeries and replaced with a Changeling. Acting in accordance to superstition, Gilpatrick gave her a cup of milk with herbs mixed in, believing it would bring his daughter back. When Margaret was murdered and Gilpatrick was called to the City Morgue to identify her body he told Detective William Murdoch and Dr. Julia Ogden that the corpse looked like his daughter but couldn't really be her. Later on, when the lead suspect, John Tucker, pointed the finger at Gilpatrick, who was brought in for questioning. Gilpatrick defended his firm belief that his daughter was replaced by a changeling and Julia's assessment that Maggie would've had to remain alive for his concoction to work, thereby eliminating him as the killer.