The glyph/code spells out REBORN.

Astrid: Walter, Agent Broyles wants to know...
Walter: Yes, yes, I heard. Well, you tell Agent Broyles that as there appears to be no unusual environmental factors to explain the rapid deterioration, that it is absurd for me to make any determination without first examining the remains...
Astrid: Okay, Walter says...
Walter: For all I know, it could be a mutation of some flesh-eating bacteria.
Astrid: He thinks that...
Walter: Some kind of alien parasite. Or... Bigfoot! Bifgoot, that's it! Astrid, perhaps you can look around for massive fecal droppings.
Astrid: He doesn't have any theories, sir.

Walter: Remarkably pungent stench.
Astrid: I'm gonna... get some scented candles.

Olivia: So has Walter gotten anywhere yet?
Broyles: Beyond his random theories of vampires and succubi, no.

Aaron Sneddon: How did your son die?
Walter: Peter was very sick. I tried for a long time to find a cure, but I found it too late and he died. And I discovered an alternate universe where another version of my son was dying from the same malady. So I crossed over to the other side with the intention of bringing him back to cure him. But the frozen lake where I created a portal between universes was unsound. And when we crossed back, the ice broke and Peter... the other version of him drowned. I lost him all over again.
Aaron Sneddon: And you... don't think you belong in mental institution?

The Observer can be seen outside of Walter's laboratory.