Peter heads to check the back, because splitting up is a GENIUS IDEA when you're looking for someone who may have changed into a vicious porcupine beast. Lincoln finds bags of medical waste in the kitchen and wonders what it's about. Olivia says she doesn't know because they didn't find these last time.
"Remember you said eventually all this would stop getting strange? In case you were wondering, it still hasn't," he says. Even in the darkness, he can tell she's looking at him blankly: she doesn't remember having the conversation. Maybe Lincoln should make stuff up! "Hey, remember I lent you a thousand bucks? When were you going to pay that back?" I mean, he might as well try to make the best of it.
Peter, meanwhile, is checking the back and finding nothing, but he is startled by a door swinging shut.
Even expecting an attack, though, I was genuinely startled by the beast jumps out at Lincoln (who is now on his own) and throws him against a wall. Olivia comes racing in and manages to fire off a shot or two at the creature, which skedaddles, and then Peter comes in. Safety in numbers, you IDIOTS.
Back at the lab, Walter is stitching up Lincoln's shoulder instead of that being done at a hospital, and humming while he does it, annoying Lincoln, as does Walter's explanation that auditory distraction dulls the peripheral senses and allows for optimal focus, which is why surgeons play classical music in the OR.
Olivia comes in to report there was no word of anyone seeing the beast that got away. As for the one they've got in the lab, Peter says they're still not sure why it died, but Walter's theory is that its cells broke down, that the rapid mutation caused all the internal organs to fail. And the injection kit with the rainbow of solutions? No idea yet either, says Peter, but they're running labs on it to try to break down the chemical composition. Peter shows her track marks on the creature's arm: "We think he was injecting himself with whatever that stuff is," says Peter, who must be some kind of forensic genius for making that leap.
Olivia finds some sort of tattoo that the Bishop boys apparently missed, and Peter calls Walter over ("Did you find his genitals, son?") to look at it. Lincoln's left to awkwardly man the tweezers holding the surgical thread, and he's defenseless in the onslaught of Olivia's apology, because she feels like if she hadn't been there, he would have called for backup. I'm not sure that's true; he didn't even mention it at the time and I can't imagine the thought process would have been, "There's a potentially murderous beast in there, maybe we should bring in some backup. Nah, we've got Olivia, we're good." Because she's worried that he didn't want to call Broyles with Olivia there, but for crying out loud, he could have said, "We're calling for backup, so Olivia, you'd better make yourself scarce." I mean, it's not like she would have listened then either, but he could have said that.