The glyph/code spells out ADAPT.

The name of Walter and Bell's old research, the Yatsko Project, is a nod to Tom Yatsko, who works on the series as director of photography.

Peter: What was it?
Walter: Bathroom! I’d forgotten that a couple of nights ago, I used my cauterizer to remove an uncomfortable growth between my…
Peter: Less information, better.
Walter: Have you spoken to Olivia?
Peter: I did. Called her last night. She’s doing better but she’s still recuperating.
Walter: I understand how difficult it is to be candid with people that you care about. Particularly when it concerns matters that are intimate in nature.
Peter: Ready to go?
Walter: Yes, I am. And by intimate, I mean sexual.
Peter: Yeah, I got that.

Walter: You understand better than most the pain a lie can inflict.
Peter: Yes, I do. Which is why, even though I expect it's going to fundamentally change how she feels about me, I am going to tell Olivia everything. Okay?
Walter: You're a good man, Peter. She knows that.

Walter: Where do you suppose I could pick up quality imported pickled herring?
Peter: No idea. Why?
Walter: I’m thinking of Scandinavia.
Peter: Scandinavia?
Walter: The Blood Eagle. A Norse method of torture... breaking the ribs and spreading them out to resemble blood-stained wings.
Peter: So we’re looking for a Viking?
Walter: Whoever did this was trained. These incisions have been made with precision. This is beautiful work. Definitely not a Viking. They were ruthless.

Peter: What is it?
Olivia: You know what Barrett said? He said that he looked into her eyes, and knew that it wasn’t her.’
Peter: Olivia...
Olivia: I understand the facts. I know that she had reams of information about me and about my life and about the people that were close to me. And I understand that if she slipped up that she would have a completely reasonable explanation for it. And I guess to expect you to have seen past that is perhaps asking a bit too much. But when I was Over There, I thought about you. And you were just a figment of my imagination. But I held onto you. And it wasn’t reasonable, and it wasn’t logical, but I did it, so… why didn’t you? She wasn’t me. How could you not see that? Now she’s everywhere. She’s in my house, my job, my bed, and I don’t want to wear my clothes anymore, and I don’t want to live in my apartment, and I don’t want to be with you. She’s taken everything.

Walter: You know what I need after a day like today?
Peter: For most people, it would be a drink, so I’m guessing...
Walter: Strawberry milkshake...
Peter: I can do that...
Walter: With extra whipped cream.
Peter: Don’t push it.