In the 2000s, he was not married and did not have children.
He was a close though not direct descendant of Squire Claude Portillon of Tranchard's Fell and bore a striking resemblance to him in appearance. He was the keeper of the WitchStar, which was passed down the generations starting from the squire in the 1650s.
He was overseeing excavation at Tranchard's Folly when he was attacked by a witch, but managed to survive by playing dead. He had the complete works of Lord Byron, including a biography of Mary Shelley. He helped Mary find information on the Varaxils in the TARDIS library, and managed to recover the WitchStar from "Lucern" and "Finicia", enabling Mary to destroy them. Mary left him the TARDIS' biography of herself, before departing with the Eighth Doctor. Shortly before her departure, Aleister guessed who she was and decided to shift his focus from Lord Byron to her and his other contemporaries. (AUDIO: The Witch From the Well)