The glyph/code spells out AGENT.

Olivia: And, uh, your father is walking around the house naked.
Peter: Oh, yeah, it's Tuesday. He always cooks naked on Tuesdays.
Olivia: Is that safe?
Peter: Uh-uh. It's not pretty, either. But you get used to it.

Fauxlivia: What's going to happen to the people over there?
Walternate: My concern is for the people of our world.
Fauxlivia: But your son is over there.
Walternate: I'm aware. Peter chose to leave. He chose his allegiance. I chose to give up my son so that you could keep yours.

Peter: Every piece of data we have about the machine points to one conclusion. Somehow, that machine was made for me.
Walter: Peter, you could die.
Peter: And if we do nothing, we're all gonna die.

Fauxlivia: That was my first commendation.
Lincoln Lee: Yeah, for dragging my ass out of a Class 4 vortex.
Fauxlivia: Well, you actually owed me fifty bucks, so I was going for your wallet.

Broyles: What do you think?
Walter: Excuse me?
Broyles: Peter's your son. As a father, do you think this is a good idea?
Walter: It's because of my selfishness, my inability to let my son go 26 years ago, that this is happening. My opinion as a father doesn't matter.
Broyles: Walter... it matters to me.

Broyles: The techs said they're ready when you are, Peter. Good luck.
Peter: If this works and I save both universes, I want you to consider me officially retired.
Broyles: I'll think about it.

Walter: I don't know my way around here. Other people, I suppose, find comfort being in chapels, speaking to You. I have no other place to turn. I asked you for a sign, and you sent it to me. A white tulip, and I was so grateful. Since then, in moments of deep despair, I have found solace in believing that You had forgiven me. I was willing to let him go. I was willing to let Peter die! I've changed. That should matter. God. I know my crimes are unforgivable. Punish me. Do what You want to me. But I beg You, spare our world.

Walternate: I know this is hard for you.
Fauxlivia: Oh, you don't know anything about me.
Walternate: Don't I? This morning in my office, you asked how I could be willing to let my son die to heal our world. But you understand sacrifice better than anyone, Olivia. You're willing to leave your son behind, to risk your life, for what you perceive to be the greater good. We're more alike than you think.
Fauxlivia: I don't understand how killing billions of people could possibly be in the interest of the greater good.
Walternate: That's because you still have the luxury of your ideals. I have to be pragmatic.

The Observer can be seen at the pedestrian mall behind Fauxlivia and her nanny, after Fauxlivia gets the page about the power surge.