Easy pertanyaan Casey. Larkin is dead. But now the he knows Kung Fu Chuck might give Casey a run for his money. Keep in mind Sarah nearly kissed Casey's pantat, keledai in the Weenie toko early on in season one. Casey ran away out the back. Since then she got the better of him twice in Vs the Colonel. Of course they were both sneak attacks.
Casey, Obviously. Even if Bryce was still alive. It's Bryce going against a trained assasin, so the choice is really easy. Its not just because Casey's one of my favs. and I hate Bryce Larkin.
I actually reckon Larkn would win. If I remember correctly Sarah almost beat the crap outta Casey at Wienerlicious, in one of the first ever episodes (possibly the second?). And Bryce is CIA, plus he's gotta be stronger (he's a guy, don't give me crap about being sexist ... I'm no a feminist plus it's biologically proven). Bryce Larkin would totally woop 'Colonel' Casey's arse.
