He is mostly known for his work throughout the 1990s on Marvel's X-Men related titles, specifically Uncanny X-Men, the main title itself, and the spin-off series that he conceived with artist Chris Bachalo, Generation X. Generation X focused on a number of young mutant students who attempted to become super-heroes in their own right at a separate school, with the guidance of veteran X-related characters Banshee and Emma Frost. He also had writing stints on Marvel's Fantastic Four, Alpha Flight, and The Adventures of Cyclops and Phoenix miniseries with artist Gene Ha.
