Banshee's first appearance in X-Men #28 isn't the introduction of a willing new teammate. He's being forced to work for Factor Three, with the Ogre keeping him under control thr…

Banshee's first appearance in X-Men #28 isn't the introduction of a willing new teammate. He's being forced to work for Factor Three, with the Ogre keeping him under control through an explosive headband. So the X-Men meet him as a threat before they understand why he's doing it. Sean is already an adult with experience outside superhero work. His law-enforcement and Interpol background gives him a different starting point from the students at the school. He's been out in the world doing a job before Xavier becomes the answer to anything. Once he's free of Factor Three's control, he helps against them. That matters more than simply switching him from a villain list to a hero list. His introduction was built around coercion, and getting the chance to act for himself changes which side he's on.