OH MY GOD
What if Parrish sees Derek at the station in that cell? I imagine their convo to go like this (after Derek stares at him for like a full minute, his eyebrows doing a lot of weird things which means Derek has a lot of conflicting emotions):
Some more staring and Parrish kinda smiles, not much, just a little twitch.
"I always knew you were trouble."
And Derek’s eyebrows go up, up, up.
"I can’t believe you just quoted Taylor Swift at me."
And Parrish’s eyebrows match Derek’s.
"I can’t believe you know who Taylor Swift is."
(There are a lot of things Parrish doesn’t know about Derek. But hey, the guy knows his dick’s size, so Derek just shrugs.)