Derek
They're all losing it. Stiles can barely read, he's having nightmares within nightmares and he isn't sure what's real and what isn't. Scott can't control his transformations; he almost turned in front of his dad who's going to get Sheriff Stilinkski fired, and Allison can't even focus on firing an arrow unless she's hallucinating that Kate is coming after her, in which case, her precision is a-okay.
And right at the end, it showed you and Peter on that chain fence thing with that electric machine torturing the fuck out of you.