I think they're going with the split personality as a power, though

I'll admit there's something up with the tattoo, but I sincerely doubt that the MPD is in any way a manifestation of Nikki's powers. The fact that she can have them when Jessica's not driving seems to give credence to the idea that they're not directly tied to the personality, and she seems to be able to turn them on and off (meaning she's not super strong all the time. She has to make a conscious -- or at least subconscious -- effort to become strong.) The MPD is a trait of her character, and -- as is often the case with MPDs -- it probably kept her alive through adversity, but ultimately it's a tool that the whole person needs to discard, because it's outlived its udefulness and become destructive.

Peter's situation is different. He's probably got a lot of emotional damage going on, which continues to exist, amnesia or no. When he was given a chance to lash out, he did. And has probably needed to since he blew up.

Victor's theory requires a bit of nuance on the part of the writers, which isn't really the show's forte.

i'm not negating that Niki has multiple personality disorder. just that Niki and Jessica weren't always one and the same, which is how i understood Jon's post.

I should have clarified, sorry. Like everyone else has said, there was a real Jessica. Another Jessica. But there's no "possession" or other supernatural/superpowered thing going on. The "Jessica" that is/was within Niki, is NOT the same Jessica that was her sister. It's just a manifestation of her psychosis.

Gotcha, Jon -- I also misread you as saying that Jessica had never existed, but as it turns out, I agree with you that she doesn't exist now.

yep, i think we're all pretty much in agreement.

Just to be clear, I also don't think that Jessica, Niki's sister, possessed her or anything. But I'm guessing that when the show's creators had Peter choke a guy telekinetically just like Darth Vader, that wasn't an accident, but a visual clue that he absorbed two powers from Niki: super-strength and an evil (well, overly self-interested, which is pretty close to evil) alternate personality.

Deader than a Norwegian Blue parrot.

Victor's theory requires a bit of nuance on the part of the writers, which isn't really the show's forte.

Well ... there is that. But it's not so much nuance as it's pretty much how MPD works. With, of course, superpowered twists. I think it's fascinating how the fact that Nikki has both multiple personalities and superpowers has led many viewers to automatically assume they're connected, when really, a real-world (ish) explanation exists for at least one of the two. MPDs aren't common, but they're somewhat more common than being posessed by spirits.

yep, i think we're all pretty much in agreement.

And now, the writers will decide that Jessica is really the ghost of her sister after all.

a visual clue that he absorbed two powers from Niki: super-strength and an evil (well, overly self-interested, which is pretty close to evil) alternate personality.

Really? IMO, it was played very different from an alternate personality. It's not like Peter wasn't aware of what he'd done when he was overly self-interested. Remember, Niki had no memory of Jessica's actions. I think his emotions just got the better of him. That, combined with the fact that he can't control his powers yet.

I think people are starting to win me over to another hypothesis, at least for argument's sake. If you look at the symbol appearing/disappearing on Nikki/ikkiN and appearing briefly on Peter, and take into account the twisted reflection of Nathan we briefly saw (which in many ways recalled ikkiN in the mirror, although more grotesque) than I'll concede, it is possible there's an evil force possessing our dysfunctional heroes from time to time, but I'd suspect it to be an outside force, and not a manifestation of Nikki's powers. Which means it might have been influencing Nikki all along. Can anyone say Nightmare Man? I mean, besides Molly?