"Exposition! in The Bathroom.

"Forgetting magic," Avi asks, washing purple pixie blood off his face with a towel in the bathroom. "Fill me in here."
"Pixie thing, and exactly what it says on the tin," Aquila replies. She's taking Avi's shirt out of the laundry machine. "They do what they do, the human mind can't handle it, then their magic erases your memory of itself."

"And exposure to their purple blood makes you immune. Which you know because you've dealt with pixies before."
"Well, yeah, we both have."

"What? No I haven't."
Aquila holds and looks down at Avi's shirt, still stained horribly with purple pixie blood.

"Wait, no, just figured it out. Woah."
"Your ratty old shirt isn't ever forgetting about pixies either, by the way."