Hmm, you bring up an interesting point. Mohinder does feel some affection for Sylar; however, the fact that Sylar is using mind control powers on him means that he will always hate him more. He acts happier here because 1) that's how he acts when he's in love, which is what Sylar orders him to be and 2) Mohinder is used to this, and more resigned to it, so it's easier for him to be happy then in the other fic.

Wow, that was long! Sorry about that. Anyway, thank you! :D