I was eying the Romeo Tank position, for all the interesting potential already built in with the backstory. Manticore physiology with damage transferral (transferred to him, mostly). Probably an older, more experienced gent. Cortana's so happy she's basically a character from Bambi with a devious streak. Liz/Beth is nuts ... clearly. So he'd probably be rather grounded. Not hating the world like your kid, but not thrilled about having no constitutional rights because he's cooler than the average Joe.
But you got there first and I definitely don't want to stomp on toes, so no worries if that's too closely related to what you're going for!