[He looks slightly surprised, but if there's a reason, he doesn't let on. He definitely regrets lying to her now, though -- or at least implying that he doesn't know Gaius as well as he does. It's going to make this more difficult, and... well, who knew it could actually be valuable to admit to a connection with that man?]

Did Gaius tell you about me? I... may have been underplaying things when I said we were only from the same universe. A lot, actually. I'm sorry, but I didn't know if I could trust you.

[At least he doesn't have to lie any more; at least not for now. This is all completely accurate, and delivered with absolute sincerity.]