If the boyos from Bad Company walked up to me, I'd beg them to let me join the unit; I mean, scoring gold 24/7 like that? That's just plain SWEET.
If Lieutenant Vasquez and SSgt. Griggs walked up, I'd warn them about the bomb in the capital... And ask for an autograph.
If Commander Shepard walked up to me, I'd buy his psionic implant off'im, and probably use it to destroy some shit!
If Laura Croft walked up.... Ah, fuck it, no-one needs her.
If Captain Bannon came up, I'd slap him across the face and yell, "Get some BALLS, laddie!... Oh, and sorry about your fucked-up childhood."
If Lieutenant Parker came up to me, I'd say, "Christ, your face is ugly... no wonder they never show it."
Et cetera, ad infinitum.