Not much is known about Callum's childhood. He was the leader of the North side of Verity. He was married to Alice Harker and had a daughter named Kate Harker. They used to live outside of Verity, but then moved to the city. Kate always wanted to go back to their original home, finally convincing her mom to take her. Callum found out about this and sent Sloan to kill Kate and Alice Harker. Sloan succeeded in killing Alice Harker but not Kate, only damaging her hearing on one side.
Kate was Callum's daughter and always strived to be like him. They had a rather estranged relationship because Callum did not want Kate in Verity with him and Sloan.
Alice Harker was Callum's first and only wife. Callum loved her, but when she tried to escape Callum said she was no longer his wife, that his wife would never do that. She was killed after Callum sent Sloan to kill her.