It will come as a surprise to no-one that Eric is only too happy to reciprocate Faith's advances. In fact, Faith can probably feel just how happy he is, given the proximity of their bodies. For once, (because, let's face it, Eric always has some kind of agenda) he hadn't planned on this happening.

...not that he's complaining. He does pull back from the kiss after a moment, however, to supply the delayed comeback: "Takes one to know one, Faith."