Knowing how precious this second chance is, and realizing that they might need a bit of a push, Walter digs out a video cassette of one of Etta’s birthdays for her parents to watch. In one of the most touching exchanges between Walter and Olivia to date, he tells her: “You must face this pain together. The pain is her legacy to you both. It’s proof that she was here. And I have experience with this, this sort of pain, and you can’t escape it by building walls around your heart, or by breaking the universe, or by vengeance. You lost each other once. But you have another chance.” He might be a mad scientist, but he makes a pretty good psychologist, doesn’t he?
Unfortunately, what neither Walter nor Olivia yet know is that she has, in a way, already lost him to the deep anger roiling underneath the still calm front. It was pretty clear from the beginning, when Peter grabs Walter’s idea of turning the wormhole the Observers use for their transport into a black hole, despite how dangerous it might be; he is too attached to the idea of a tangible victory, something real he can hang onto. Most probably Peter’s action were not only motivated by anger at Etta’s death, but also at his anger at Olivia not getting the chance of once again breaking down her walls. However understandable that may be, revenge is dangerous business; as Anil puts it, "before you go on a journey of revenge, dig two graves." And when he loses that tangible victory he so desperately was looking for, Peter seems to have lost all hope, and the darkness of despair takes over. In a way, he sold his soul, choosing to use the Observers’ tech to beat them, even if the price is to become emotionless like them. The question then becomes, how could Peter have channeled his anger into actions that were healthier, albeit not with as immediate results?
The Observers are of human origin, and yet they are nothing like us, for they sold their humanity for the sake of technological advancement. Their view of one aspect of their humanity, that is, their emotions, is quite telling: “Emotions get in the way of judgment.” Without this, their higher, emotional/spiritual nature, the scientific advancement they achieved was seriously perverted, as we can see through their actions. Anil’s jeer of “That’s the cold stare that I know and love” left me particularly cold blooded after Peter’s choice at the end of the episode. Too bad the Observers did not retain their human side; imagine what kind of work they could have created had they balanced the technological advancement they achieved with an even basic code of morality.