Right near the beginning of the episode, Olivia comments upon how unfair it is that they just got Etta back only to lose her again, and I totally agree with that, as that was my reaction to the previous episode. Etta's death was and is heartbreaking for that reason, and back during "The Recordist" (5.03) episode, Peter tells Olivia, after she tells him that she had always felt like she wasn't worthy of Etta, that he doesn't know why but their family has been given a second chance, a chance that he is going to take, and that only makes her death even harder to swallow. I love how Peter finds the concealed C-4 in Etta's apartment and says, "That's my girl." This reminds me of David Robert Jones saying the same (only in much creepier fashion) of Olivia after she turns the lights off in the "Ability" (1.14) episode, therefore, in my opinion, giving more weight to my David Robert Jones being Olivia's biological father theory, even though we now know that that isn't the case. This episode is a close examination of humanity and how we deal with trauma differently. Olivia basically shuts down and tries not to respond to it but fails, as she can't help but cry. She is, in a sense, in denial, because she refuses to watch the video recording of Etta's birthday, and I think that her finally deciding to watch it is a sign of an emotional awakening, a rise from numbness. Peter, on the other hand, is filled with rage, and his heart understandably becomes vengeful; this is a man who lost someone whom he held very dear to his heart, right up until the bitter end when she was taken away from him, and even then, he refused to stop looking for her right up until the moment that he had to amber himself. He is shattered, and he deals with pain via anger.
The Observer whom is captured by the Resistance, the one interrogated by Peter, says to Peter, "You blame us for her death," and that is an understatement. Peter has every right to blame the Observers; even though it was not that specific Observer who killed Etta (that would obviously be Windmark), but this isn't really a witch hunt because it would seem that all of the Observers who are here are here for the same reason - to conquer and destroy, which is honestly not the outcome that I had been expecting of this episode. When I saw from the promo that an Observer would be captured, I wondered if, maybe, we were going to see an "I, Borg" (episode of Star Trek: the Next Generation) kind of scenario in which we would meet a "good" Observer (other than September and the calendared team, that is) who would display individuality and an understanding of the human race, but that is not the route down which we ended up going, as this Observer is just as nasty as the rest, and Peter, by the end of the episode, kills him. Walter, though, seems to be the most sensible of the Bishop family. One can easily tell that he, too, is grieving, but he seems to be the only one in a healthy state of mind, which is ironic; it is very ironic that now, Peter is the one out to cross some lines while Walter is the one trying to talk some sense into him because the reverse of that always used to be true. Astrid (or should I say Abner?) seems sad, too, but I don't think that she has taken it as heavily as the rest of them because she didn't get to know her as well; she spent most of the time that Etta was with them in the lab, and we didn't see many scenes between her and Etta, unfortunately, but I love scenes between Astrid and Olivia because there aren't that many (another memorable one that comes to mind is from "Marionette" (3.09)), but when we do get one, it's really great.
Walter tries to convince Olivia to watch a video recording of a birthday of Etta, and she says, "Walter, I am holding on by a thread." I really like what we see from Olivia during this episode because some people seemed to think that Olivia's reaction to Etta's death at the end of the previous episode was empty and lacked any depth, and while it is true that she didn't really cry, I think that she was in shock, and we certainly do see her cry now. We see that she is in emotional turmoil and is trying to hold herself together until she finally loses it and falls apart at the end of the episode, an incredibly heartbreaking scene especially because of the emotional impact of the video recording (seeing Olivia and Peter happy together like that has been something for which we have been waiting a long time). Walter delivers a beautiful speech to Olivia, trying to console her. He says that he understands the grief of losing a child and says that building walls around her heart, or breaking a universe, or seeking revenge, will not absolve the pain. I love, though, how we do see her a bit vengeful (although not to Peter's extent) when she shoots the Observer who almost bashes Peter's head in with his foot. She says, "Yeah, it is that type of gun," a great line, and it's comical when the Observer tries to catch the bullet but fails. We see during that scene just how physically strong the Observers are, which is pretty darn strong. We learn from this episode that the Observers apparently think of themselves as god-like, at least in comparison to us, and this is evident from the captured Observer's comment regarding their viewing us as an ant colony to be crushed. He also says to Peter (twice) that "you don't even know what you don't know," and initially, this really confused me, but after some thought, it would seem that he is saying that we aren't even aware of the knowledge that we could have but simply don't.
Peter is very close to a Jack Bauer throughout this episode (hence my Bunsen Burner rating), and the only other time that I can think of that we have seen Peter anything like this is during the "Reciprocity" (3.11) when he goes on a Shapeshifter killing spree. I would say that this is far worse, though, which makes a great deal of sense considering how much more personal that this is to him, but both episodes share similar final scenes.
"Reciprocity" (3.11) - final scene
"An Origin Story" - final scene
As much as I love this scene, it seems farfetched that neither Peter nor Olivia notice these as they drive down this alley, nor does Peter notice them as he rans down the alley before Olivia notices them, but I digress. Peter ultimately removes the chip from the Observer, and I wonder if the Observer dies because the Observers can't survive without these chips, and if it's the latter, does that mean that Peter now has to spend the rest of his life with this chip implanted? I doubt that we're going to see him sporting a fedora and a suit (although it's apparent that the writers did have this planned out for a while since Josh Jackson was dressed as an Observer in a season 4 ComicCon video), but I do think that we will see him with newfound Observer abilities. After all, since Olivia presumably doesn't have Cortexiphan left in her system, perhaps, Peter will now be the superhero. I also wonder if the title has to do with something other than Peter saying the Observers origins are human but also has to do with the possibility that Peter having inserted the chip into his neck is what ultimately creates the Observers. I was happy to have seen Walter demonstrate a scientific explanation (I wonder why it didn't work, though - why wasn't the wormhole successfully collapsed?) with toys; that made it feel a bit like old Fringe. This is, again, an excellent episode; season 5 now has me hooked.