Why does Olivia remember things that she shouldn't? Will Peter be freaked out by the change, or happy that "his" Olivia is coming back? Last night's episode of Fringe played with the limits of reality once again, leading to this week's five questions about "A Better Human Being."

What Is Going On With Olivia?

If we're to believe Peter's intuition, then the memories Olivia is recovering are, somehow, the Olivia from the first three seasons of the show… but how, exactly? Apparently, Walter has worked it out and the answer has something to do with Cortexephan, but sadly we weren't given the explanation: Is Olivia crossing over with other worlds, and retaining the memories of all the alternate Olivia she's coming in contact with? Is this Olivia's abilities nothing to do with the ability to cross between worlds, but instead something to do with her empathy, as per Walter's comments about what she was like as a kid this episode, and Cortexephan is simply boosting those abilities just like it boosted the earlier Olivia's? Or is this something different altogether?

What Is So Important About Cortexephan?

If this Olivia doesn't have the ability to cross between worlds naturally, but instead has some other latent power, then perhaps she's been a red herring all along. Maybe the fact that she's been being kidnapped for tests that she doesn't remember has less to do with her abilities and more to do with the fact that a test subject who'd react to Cortexephan was needed for some reason…? What if, again as per Walter's suggestion, someone has taken the original 20 Cortexephan samples and has reverse-engineered it, and has just been using Olivia as a guinea pig to make sure that it worked…? If that's the case, then…

What Is David Jones' Plan?

If, as the final scene of the episode suggested, Nina isn't actually involved in this - or, at least, not the Nina that we knew - then everything seems to be coming back to David Jones again… So why would he care about Cortexephan or Olivia? Is the clue in what's happened to Olivia, perhaps? I'm beginning to wonder if the fact that David Jones was last seen in the old timeline is actually more important than we've been led to believe, because...

What If Peter Is Doing This?

Well, after a sense. What if Peter's idea of being able to go home is based on faulty thinking, and that what we'd all originally thought was happening - that this is Peter's Earth, but with a different timeline after the Observers' tinkering - is actually the case. What if Olivia's memory isn't being overwritten with the Olivia of another world, but instead being restored to what it was, originally - She said that her old memories were "hazy, like a dream," which feels like it could be an important line; what if Peter has always been home, and it's not that history was rewritten, it's just that the Observers somehow managed to make everyone think that it had been…?

A flaw in that theory: Lincoln should be dead, if that was true. But, of course, given all of Fringe's other plots, who's to say that Lincoln is even Lincoln? Which reminds me...

If That Was Nina At The End, Then Who Is The Other Nina?

So let's assume that the Nina in the chair at the end was the real Nina… Does that make the Nina at Massive Dynamic a shape changer? We've known that they've been on the loose, and working for David Jones, for some time, after all. Or what if it's the Nina from the other Earth? Of course, it's just as possible that the Nina in the chair is the other Nina or a shape changer as some kind of attempt to mess with Olivia's head… Next week's episode should be a very interesting one indeed; at this point, can we trust what anyone says…?