feel free to add others in the comments.
Sandman: Every time I become a hero, I get the feeling that my history is rewritten so I'm back to being a villain again.
Deadpool: I have tumors covering almost 80% of my skin and laugh because if I didn't, I'd cry uncontrollably.
Sabertooth: Do you really want to know my backstory? <switch to therapist rocking back and forth in the corner>.
<seriously creed's history is bloody horrific>.
Beetle/Mach/Abe Jenkins: Why do I have to keep coming here? I became a hero decades ago. No I'm not here because I'm a middle aged tech genius attracted to an awesome ex villain who decided that we should "just be friends." No my power armor isn't my response to a mid life crisis.
Random: I literally am a child trapped in an adult's body...bloody mutant traits.
Rogue: I kissed a Spaceknight and I think I liked it so much I became a hero. Now only if Mom understood.
Spiral: Yes, I'm a horribly overworked and under-appreciated super-genius whose horrifically deformed thanks to her boss. Thanks for noticing. I should put you on a reality tv show for that.
Mystique: I'm over a hundred years old you clod. It didn't work with freud and it won't work now. A side effect with living that long is you leave a ton of loved ones behind.
Yeah, Creed and I stay in regular contact for one reason more then any other: we know the other one will still be around.
M.O.D.O.K. : I was the original deformed test tube baby and your wondering why I'm antisocial?
Omega Red: I'm a living weapon from a lifetime ago whom was never used. Weapons have feelings too you know.
Taskmaster: Sorry whom were you again?