Of all the people best-equipped to deal with altered realities and venturing into them, you'd think that Walter Bishop would be at the top of most lists. But, as Friday's Fringe demonstrated, things aren't always as they seem... Here're five questions about the wonderfully-titled "Through the Looking Glass and What Walter Found There".

Who is Donald?

For the second time this season, we find out that someone called Donald - who Walter doesn't remember, and the show seems suspiciously determined to hide from our view - helped Walter organize the plan against the Observers before the Fringe team was ambered. It's clear that Walter's identity is going to end up being something that's important to the overall arc this season, which makes me wonder if we've already met Donald, in some other guise. My guess, based on little other than a suspicion that I'll partially explain in a second? Donald is Captain Windmark. That's why Windmark is so obsessed with capturing Walter, and yet can't quite manage to do it…

Who is the "we" that helped Walter design the Pocket Universe? (And how did they do it?)

"We designed this for you," VideoWalter said. But since when did Walter have the knowledge to construct alternate universes, never mind designing them so that they resembled Escher paintings? Was Donald part of the team…? Or was September, the Observer that crossed sides and teamed with the Fringe team at the end of last season, responsible? If that last option is the case - and it seems to be the most likely option at this point - then what else did he help Walter do before his disappearance?

Who is the child?

The questions of who the child Walter abandoned in the Pocket Universe was and why he needed to be hidden there were central to the episode, and left entirely unanswered purposefully. He was an apparently integral part of the plan to defeat the Observers, but why…? (Weirdly enough, the fact that he came from some Fringe case that Walter doesn't remember struck me as odd, as well. Did the Fringe team have cases after the Observers invaded? Doesn't that strike anyone else as weird?) Is he an empath, as Olivia assumed? Is he an Observer? Some kind of human/Observer hybrid? Either way, expect to see him again before too long, I suspect.

What is Happening to Peter?

The "you have no idea what you've done to yourself" taunt that the Observer gave Peter before Peter managed to teleport and kill him was one of those classic action movie moments of ridiculously unsubtle foreshadowing, but it's clear that Peter is gaining access to all manner of powers, even if they don't apparently come naturally to him yet (Note that he didn't apparently see the portal to the Pocket Universe first time around, nor did he immediately have access to increased speed and strength in the fight; maybe the powers have to be "activated" in some way?). The Observer Vision moment at the end of the episode seemed to be a surprise as well, however, and raised the possibility: What if Peter becomes an Observer? As in, not just having the same power, but actually becoming an Observer, with the same attitude and affiliations? And what if this is something that happened to Donald earlier, (a) transforming him into Windmark, and (b) explaining what the resistance hasn't just implanted themselves with Observer tech at some distant point in the past if it's as simple as it looked last week…?

What is Happening to Walter?

The idea that Walter's brain regrowth - from "Letters of Transit" last season - is continuing to affect him post-brain-scrambling was a nice one, as was the implication that it's creating a "different" Walter. They didn't go as far as to suggest schizophrenia, but it was certainly implied by the way that Walter talked about his actions as "not something [he] would do." Walter, again, becomes the mirror of Peter's situation, and the more moral of the two, worried about what he'll do in the name of "winning" and sharing his fears about the transformation while Peter does whatever he deems necessary without pause, and keeps everything to himself. Who could've expected that Fringe, always a show about fathers and children, would end with a season in which Walter and Peter's journey becomes the same, but entirely different?