Going by the name Doom:
Once, Crash was Doom's military instructor.
Long after everyone else on Phobos was dead (the only other survivor came to be known as Phobos (character)), he kept fighting, determined to send out a warning to Earth before the demons could claim him.
Distracted and intelligent sounding, (but not a member of the intelligentsia, more like a well-educated tradesman) this guy may be a few cards short of a full deck, but his training serves him well. He's a bad-ass in the arenas.