Banshee

History:

As an Interpol agent, Sean encountered the serial killer Arkady Rossovich, who would later become the Soviet Super-Soldier Omega Red, and was approached by Magneto, before the events at Cape Citadel occurred. Following his wife's death and his daughter Theresa's abduction by his cousin Tom, Sean made his way to New York, where he joined the NYPD. As an NYC cop, Cassidy met his future co-headmaster Emma Frost (White Queen) and saved her from a less-than-coherent Dark Beast, although the memory of the event was then wiped. Later, the leader of Factor Three found out about Sean's mutant powers and captured him, placing a device on "Banshee's" head that would explode if he didn't follow orders. It was then that Banshee first came into contact with the X-Men, who fought and then freed him from Factor Three. Banshee was captured again by Factor Three and forced to do their bidding, but was again freed by the X-Men. He ended up in Nashville, where months later, he was recruited into the new X-Men for their first mission to Krakoa. Banshee remained an X-Man until he was injured in the battle with Moses Magnum. Following the battle with Proteus, he stayed on Muir Island with Moira MacTaggert, and the two have been lovers ever since. After the Mutant Massacre, the surviving Morlocks were transferred to Muir, and Banshee was healed by the Morlock Healer. He aided in defending the island against the Reavers, although he was shot in a pre-emptive strike (he was again treated by the Healer). Afterwards, Banshee and Forge left in search of the X-Men, who had apparently died in Dallas months before. They contacted X-Factor, and eventually were found by Storm and Gambit, not long before all of them were captured and taken to Genosha for trial. Banshee finally left the X-Men after his jaw was broken by a genetically-mind-altered Gambit to chase after Moira, who had left in grief over her being forced to do the altering by Magneto. Banshee was back at the Mansion for the Phalanx's attack, and along with Jubilee, Sabretooth and the White Queen, went to contact the next generation of mutants and save them from the Phalanx. Afterwards, Banshee joined Emma as the headmaster of the School for Gifted Youngsters, now located at Frost's Massachusetts Academy.