Ceased to exist after touching his "father", Jamie Prime, and being reabsorbed into him
Powers & Abilities:
infant duplicate of Jamie Madrox
Sean Madrox was conceived in X-Factor (3rd series) #10. Believed to be the natural child of Siryn and Multiple Man until his birth, Sean was actually a duplicate of one of Madrox's duplicates who slept with Siryn. Like any dupe, he was tragically reabsorbed in the main Jamie when they first touched.