His part in the issue is brief — merely shown in the first few pages berating his team of mutant assassins known as the Marauders — but in the larger arc he would ultimately establish himself as a formidable force with which to be reckoned.
It wasn’t until 1996 and the limited series The Further Adventures of Cyclops and Phoenix that his full backstory was explained.
In the late 1980s, writer Chris Claremont and artist Marc Silvestri got a bit tired of constantly returning to Magneto and the Brotherhood of Evil Mutants as antagonists for the stories they were writing in X-Men comics.
So when it came around to writing Uncanny X-Men #221 for release in September 1987 (part of the “Mutant Massacre” storyline), they took the opportunity to introduce a whole new kind of baddie of the mutant heroes.