Felix's boyfriend.
From reading the youtube comments on the Webisodes, I'm not the only one who thinks this, but what made me go "hmm" is webisode 8, where they're in the Raptor on the search and rescue mission, there's a red light reflected on the lower right of his helmet; at a couple of points it's angled so that it looks precisely like the back-and-forth red light on a Cylon helmet. And he did give Felix the morpha that was eventually used to unpleasant effect.
I believe Felix has figured it out - I believe that's why he tells him to keep his head down and he'll protect him.
(either that or we're being manipulated to -think- it's him...)