Well, I think the main reason he acts evil when there is no "audience" is a bad one, but, because it's a TV show and the writers want to keep us in the dark. It could be explained away by him not knowing if someone might see him or overhear him, weak I know, but if they want to keep the audience guessing

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Yes, he did hurt Cordelia, but instead of hitting her in a vital spot (that I'm pretty sure Angelus could have) he hit her in the leg. Also, at one point he had her unconscious and alone (when he escaped from the cage). Instead of killing her he locked her inside. That's twice he could have killed Cordy and didn't.
I've seen that episode twice now (I get it on Tuesdays in Canada), and boy, when he was pumping the Beast for information on it's Master he was nearly as obvious as when Andrew was wearing a wire and trying to get the First to talk about its weakness.
Also, I still think it was awful convenient that Angelus didn't do anything in the fight between Faith and the Beast (hoping that Faith could take the Beast maybe?) until the Beast was just about to kill her. He could have waited untilt he Beast had killed her before killing him if that was his plan.
I'm willing to say that I'm off base, but after viewing Angelus pumping the Beast for information it just felt more like an Angel thing to do than an Angelus.
Again - I've changed my mind with the whole baby thing (I forgot that the Father will kill the son was a fake prophecy). As for it being the First, I know it can't touch anything so that's why that's a REALLY weak theory (unless it could possess her or something because she's part demon). It was more of a guess to somehow tie the action on Buffy and Angel together. It's probably something else working with the First.
IceBear