He doesn't have to do much to rouse her. Calling her name a few times does the trick easily enough; her eyes shoot open with a start, and she sits bolt upright with a sharp inhale, and turns to look at him.

"Oh," Peridot says, blinking a few times, trying to get her brain to catch up with the rest of her. Her usually geometric looking hair is all fucked up in the back from the way she was laying, and it's not a great look. "...OH. Stars-- You're awake--" She scrambles down off the window seat, snatches up the healing draught that Lambert left behind, scurries over to Childermass, and... awkwardly holds it out for him to take.