The duo we all know and love (well, all five of us that read title) from the X-Men 2099 team. Skullfire, the guy that can suck energy from anything and shoot you in the face with it and the wild yet lovely psychic vampire Luna. That's amore. :)

Anyway, Skullfire is majority GI Joe since I think he's supposed to be a bit shorter than Luna.
-head: GI Joe Retaliation Roadblock with Marvel Universe Mystique hair.
-torso: GI Joe Retaliation Roadblock with (I believe) GI Joe Pursuit of Cobra: Cobra Commander arms and coat.
-legs: GI Joe Buzzer (I think)
-feet: Marvel Universe Loki

Luna is just a repainted Marvel Universe Valkyrie with sculpted hair, bracelet, and collar studs.

Thanks for looking.