Joshua Jackson Joshua Jackson

[Warning: This story contains spoilers from Friday's episode of Fringe.]

Fringe's Peter has returned!

After Olivia (Anna Torv) and Walter (John Noble) both realized they were having visions of the same strange man, they set out to discover his identity. Considering that Peter (Joshua Jackson) took the form of a bright blue blob of energy — a side effect of trying to cross into the timeline — he found them first. After observing The Energy Blob absorbing all things metal, they mistakenly assumed that it was actually a rogue cortexiphan patient Olivia had previously encountered who had the ability to project himself . Although they hunted down the subject in question, turns out he wasn't responsible for The Blob, but could destroy it.

Fringe Scoop: Peter returns... but no one remembers him!

Fortunately, realizing it was literally the man of her dreams, Olivia stopped the patient in time, though he still seemingly provided enough juice for Peter to reappear in corporeal form at Reiden Lake, the site of over-there Peter's death when he was a boy.

So, Peter is back — but no one remembers him, as showcased when Olivia said, "Who are you?" Who is he indeed? Since this is the convoluted world of Fringe, we need to get acquainted with this new Peter, so we've compiled the five things to know about him and the reality he's facing now that he's returned:

1. Peter 2.0 is definitely an upgrade: Peter is technically the same man we've come to know and love, but he isn't the man we first met. "Because the guy that we met in the beginning of Fringe had no desire to be there, and slowly but surely got warped into this, as John and I described it, fanboy," Jackson previously told us. "In the course of doing that, he kind of went from being the impetuous teenager of the show to kind of sulking in the corner, to actually being a man. And the guy who would come back to the show after having sacrificed himself for the love of his family is a different man. I think he's grown up a lot. I think a different guy comes back than the guy that left."

2. There will be trust issues: They may not know him, but Peter still retains all of his memories of them, which will cause the Fringe Division to put him on lockdown. "When he shows up claiming all these things and knowing all these things, it's really freaky," Lance Reddick says. "Broyles' attitude is that it's possible what he's saying is true, but the last place I'm going to do is to believe him... at least at first. It has to reach a point where there's so much validity to the information that he has and the way that he helps, that over time, he's given more and more trust and more and more freedom to operate, work and help."

Fringe Bosses: Peter never existed, but the last three seasons still did

3. Peter and Walter won't be playing catch anytime soon: Poor Peter, he probably expected a warm welcome from his father, but all Walter sees is the man who has been haunting his visions. "'Oh hi there, I'm your son' — It's not going to be, 'Oh thank goodness for that,'" Noble told us on set. "As much as Walter may want it to be [like that] — and we'll see an element of that, but we can't resolve that too soon, so we've got to build that thing through. There will be some resolution in the first half of the season."

4. Peter and Olivia aren't sitting in a tree: Oh, how we wish it were like old times and they would just fall into each other's arms, but Torv says, "In this timeline, Olivia doesn't know who he is, and in Peter's timeline, it took them a long time to get together, so..."

5. Baby Henry isn't even a gleam in Peter's eye: Just because Peter is back, doesn't mean his baby with Bolivia automatically will be, too. "It's not possible if they've never met," Torv says. "Unless we end up going back to the other timeline, which may happen."

Are you excited that Peter is back? Sound off in the comments!