"And Those We've Left Behind" is an interesting episode because we receive a couple of answers regarding Peter's disappearance, but not very many, and as is the typical case when it comes to Fringe, these answers only lead to more questions. For example, this episode reveals that Peter was not consciously trying to make his presence known during the past few weeks; he is both surprised and confused when Olivia tells him that Walter has been seeing and hearing him around the lab and says that he was not responsible for that. That, of course, only leads to a major question - why, then, was Walter seeing and hearing Peter, and why was Olivia dreaming about him? Sure, I could buy Peter's theory, which is that Walter and Olivia have ties to the old timeline, but, then, why would Walter hear Peter crying out for help? Then, there is the dream at the beginning of the episode (which I immediately knew was a dream), and in the dream, Peter tells Olivia that it took him three years to get to her, and I wonder if that's accurate. Based on what we know from the comics, that sounds about right, since the journey upon which he embarked certainly looks like it took a while. However, isn't that, then, a continuity error, since he doesn't seem to understand why no one remembers him? If he has none of those memories, how did he know that finding Olivia took three years?
Peter asks Olivia if in the dreams that she had about him, the two of them were at a park while Walter was swinging on a swing set, asking her if she felt a connection to him in the dream, and she replies, "You're a stranger, so what would I feel?" I don't believe her, since she cleverly finds a way around answering the question without actually answering it. I think that that is exactly what her dreams were like, but she doesn't want to admit it because she's afraid of what that could mean. This season, we are, in many ways, seeing season 1 Olivia again, the Olivia that was terrified of opening her heart to someone, so the idea of eventually doing that again is not something with which she is on board, which is why Astrid receives a firm "no" when she suggests to Olivia that she should try to hook up with Lincoln. It is clear that Lincoln likes Peter, that, unlike anyone else, he trusts him, but unfortunately, my Pincoln fantasy ship is no longer on the playing field (not that it ever was), because Lincoln expresses an interest in Olivia in this episode. We also see that Broyles is warming up to Peter a little bit. Near the end of the episode, Peter tells him that he had been thinking about this problem the wrong way, that the timeline isn't the anomaly; he is, and he needs to try to find a way to get back to where he belongs, and Broyles seems sympathetic.
I don't think that Peter's conclusion is true, though. If this timeline has nothing to do with the timeline that we have known for the first three seasons, why show it to us? If these are different Olivias, different Lincolns, different Walters, different Astrids, etc., why do we care about them? Why should we care? Also, if Peter wasn't intentionally trying to bleed through, then why was he bleeding through? First, he says that Olivia and Walter must have been seeing him because he is tied to their timeline, but then, by the end of the episode, he says that he doesn't belong here, and he doesn't proceed to try to explain, then, why Olivia and Walter were seeing him. If he doesn't belong there, then that means that somewhere out there, there is a timeline in which Olivia and Walter noticed that Peter went missing and have since been trying to figure out where he went, and if that's the case, how is this not a parallel universe? We know it's not because of the test that Walter has Astrid conduct, which confirms that Peter is not from a parallel universe, which, of course, shoots xerophytes' argument down. It is interesting, too, how near the end of season 2, Peter was upset with Walter and didn't want anything to do with him, and they have now switched those roles; Walter wants nothing to do with Peter, calling him "it" and "subject" in the process.
Also, the team apparently comes to the conclusion that the time slips began about three days ago, but that is not true, because Olivia experiences one near the end of "Subject 9" (4.04), and it's annoying that she doesn't bring that up. Sure, at the time, she may have dismissed it as lack of sleep or something to that effect, but one would think that she would now attribute some sense to it and bring it up, but I honestly think that that is just sloppy, inconsistent writing, and Fringe is my all-time favorite show, so you know something is annoying if I am knocking it. I have to wonder, though, why Walter owns housing on campus? If he lives in the lab, why does he have a dorm? Why would he be paying for that? Is it something else bleeding through? Perhaps, the longer that Peter stays in this timeline, the closer it will get to the old timeline? I really like the scene between Peter and Olivia in the car, because throughout the first three seasons, we see many scenes between them in the car, so I think that it was supposed to be a sentimental scene. I also love the scene between them near the end, in Peter's new housing. Olivia finally warms up to Peter a little bit and believes that he is from an alternate timeline. She recognizes that where he is from, she was important to him, and she shows him some kindness and respect.
Peter totally looks like Walter when he is mapping out theories on the board, and I find that funny because there was a day which he would have resented hearing that, but now, I think that he would accept that as a compliment. It's funny how, even after discovering that the man stole him from his parents when he was a child and then lied to him during most of his childhood, he still looks up to him and sees him as his father. We still see a pretty arrogant Peter, but I guess that he wouldn't be Peter if we didn't; he has a really smug look on his face when Olivia tells him that she was dreaming of him, and I am still really happy that the "Man in the Mirror" theme continues to be heard; Chris Tilton is truly a genius for having written that. When Raymond Green finally turns the machine off, for a second, I thought that Peter was going to disappear again, and to some extent, it would have been really funny if he had. Stephen is an interesting character, because like so many Fringe villains, he isn't truly a villain, as his intentions are ultimately good. He doesn't realize that what he is doing is killing people; he thinks that the time bubble is only affecting what is inside his house. Obviously, the science is different than that of "White Tulip" (2.17), though, because what Raymond is doing is causing time anomalies, but not resets; not everyone is affected.
Raymond wants to revert back to a time at which his wife, Kate, did not have Alzheimer's Disease, so we see the common, prevalent theme repeated once again - how far would you go for someone that you love? Kate makes a sacrifice; she completely crosses her equations out so that Raymond can never attempt to build the time bubble again because her belief is that "some things are supposed to remain theories," which I find interesting because why, then, would you even bother with it, especially since she was spending so much time on it? Her sacrifice makes this episode really sad and beautiful, and what is really neat is that the actor (Stephen Root) and actress (Romy Rosemont) are actually married. It's funny how Stephen was able to get the machine to hold the time bubble for forty-seven minutes, that number again, and I just got done watching Star Trek: the Next Generation for the first time, in which I noticed that number repeatedly, as well, even more so than J.J. Abrams' shows, and although it is not a J.J. Abrams show, Raymond conducting his work in his basement really reminds me of Sliders, another series that focuses on parallel universes but in a much different way.
Once again, the episode's episodic storyline is reflective of the overall arced storyline; Kate contracting Alzheimer's and consequently not knowing who Raymond is is reflective of Olivia not knowing who Peter is, and since this episode fits so well with the overall question of the series ("How far would you go for someone that you love?"), I am left to wonder how drastic the path will be that Peter takes to get to his destination, which is to be with the Olivia that remembers him. From the BEYOND THE FRINGE comic book series, we know how Peter has already gone, but ultimately, the outcome is not what he had desired, so how much further will he go? The episode definitely offers its rewards; for example, the plug that goes into the back of Peter's neck is a really nice shout-out to Olivia's "trips" to the tank back in season 1, and although I do know that the Faraday cage is real and is not fictitiously exclusive to the Fringeverse, I think that the inclusion of one into this episode serves as an intentional reference to Daniel Faraday of LOST. However, I really expected the time anomalies to be more closely linked to Peter's return, especially considering the fact that Olivia experiences one near the end of "Subject 9" (4.04), which supposedly never happened, and I am also annoyed that we have still not seen how the Observers are responding to Peter's return; I give this episode a somewhat modest rating of 7 Faraday Cages.