Alistaire is a brilliant scientist, chief of research for W.H.O., a military organization who studies paranormal happenings in British territory. He met Excalibur at the beginning of the Cross Time Caper Saga, and got caught in the vortex of Widget, traveling through the dimensions with the team and becoming a good friend of them.
Alistaire used to love Rachel (Phoenix) who of course wasn't interested in him, not like Kitty Pryde, who became the third player of the game, developing some real funny situations due to this triangle.
Anyway, things turned bad when he discovered in an excavation in Scotland, in the company of Kitty, the lair of Necron, a powerful and deadly sorcerer from other dimension who wanted to destroy this world as he had done with his own. Phoenix vanquished him, but unfortunately, went comatose after that. The worst day of Alistaire's life was still to come, when his sister Alysande was accused of treason and murdered later by Jamie Braddock. Alistaire met Nick Fury after burying her and got some documents which cleaned her reputation, but his appearances decreased since then.