I'm going to go out on a limb and say Arthur Petrelli and his Pinehurst crew are the villains here. This obviously makes Arthur extraordinarily dangerous at this point since he stole Peter's powers with his vampiric power absorption ability. This makes things rather interesting as Peter seems to be completely powerless at the end of the episode. However, is this really the case?
As best as could be seen, Peter only tried to use one of his former powers after hugging his father. Now, as I have stated before, the precise natures of some of these powers are somewhat vague - for example, the Haitian's power inhibition ability and Daphne's ability to move even though Hiro froze time. Many of these powers certainly have been shown to have limits. This is what makes Arthur's ability so interesting. What are its limits?
What is clear about Arthur's vampiric ability is that it, as opposed to Peter's power mimicry ability, has to be an active ability. The reasoning for this is that had it been passive, there would have been no way Arthur could have taken Peter's powers. And the reason for this is that before Arthur and Peter hugged, Peter had already acquired Arthur's power, and if it were a passive power, their contact would have (or it seems logical that it should have) completely negated the power transfer.
Now going back to the questions that I posed earlier, I think that there is definitely a loophole left by which Peter can regain his powers. (And it seems as if at some point Peter has to regain his powers since he and Sylar are probably the main stars of the show.) My guess is that perhaps Arthur's power is limited in that he can only steal powers that he doesn't have. This would mean that Peter would retain the powers that Arthur had already demonstrated prior to the embrace (namely, cellular regeneration, power absorption, and telepathy). This would perhaps be the best way that Peter could plausibly regain his powers. Obviously this is all just speculation, but there is one more question that I have about Arthur's ability that cannot yet be answered. Does Arthur have the ability to transfer powers he has absorbed to other people?
A few other notes:
- I can understand now why in her dream Angela Petrelli heard Arthur say that she would not be able to move. This is because Arthur is likely planning on taking Eric Doyle's puppet master ability. Eric Doyle should be eliminated not solely to prevent this from happening, but also, and primarily, because he is extremely creepy.
- At this point I cannot figure out just what Mohinder is doing in acquiring all of these other people. Is he planning on studying them to find a clue about abilities? Is he planning on eating them? That's it; Mohinder is the dumbest character on this show. In truth, Matt Parkman literally has considerably less intellect than Mohinder, but we don't expect Parkman to do intelligent things. Mohinder is (was) a genetics professor and so we should expect more out of him than the colossally stupid things he has done this season.
- Angela Petrelli should have allowed Sylar (or Gabriel) to slice open Peter's head and acquire Peter's ability. I'm sure she doesn't want to see her sons battle it out, but at the point after Peter attacked her she should have realized that Peter was a loose cannon and Gabriel (no, I don't think that I'm going to call him Sylar anymore at this point) was the one that could be counted on. Gabriel would have been much better prepared for the confrontation with Arthur, and likely would have singlehandedly wiped out all Arthur's assembled crew.