That is pretty sad. Greg looked like he could really use a friend in that situation. What happened to Greg with the bugs, it wasn't his fault, and I don't think he was evil, so much as he was working from instinct and there's no derailing that for him once he got infected.

There's also a pretty creepy parallel between Greg and Clark in this episode, and I don't know why they did it, with the watching of Lana when she doesn't know she's being watched and leaving her gifts. Greg's final "instinctual" acts of mating remind me of "Crimson" when Clark finally abducts her and takes her away to his barn (which he can't help at the time because of Red K). I doubt they meant for it to work like that. But I don't know.