I never made it through more than the first few episodes of X, so all my knowledge of the characters comes from Tsubasa's Acid Tokyo arc.

If Steve & Tony are Subaru and Seishirou, then who are Kamui and Fuma, X's other warped shonen ai pairing?

edit: Seanchai's just told me that in order to do an X/Marvel fusion, you'd really need to go to the X-Men to get the right degree of creepiness in relationships. Or the DCU, for vague pedophilia.