Holy shit. The X-Men certaintly aren’t Batman. Or Superman. There is no dialog here about resisting the urge to sink to your enemy’s level, or about losing your soul should you succumb to the temptation of taking a life in the heat of the moment. When push comes to shove the X-Men start murdering as hard as they possibly can. Look at Riptide. Colossus practically tore his god damn head off. (Uncanny X-Men #211 – Nov 1986)
This scene (this whole story arc actually, but this scene in particular) changed my perspective about superheroes when I was a kid. Dark stuff.