Oh man, oh man.
All the little things.
The fact that Derek was actually worried. That he believed Stiles (and Scott, but lbr Stiles was crying and Derek asked Jennifer about Stiles’ dad).
The fact that when Stiles fell behind to use the bat on the twins, Derek rushed to help him.
The fact that Stiles knew about Derek dating Kate. (HOW??? We just don’t know).
The fact that Derek is past exasperated indulging when it comes to Stiles. He just takes it in stride, considering his suggestions seriously. (I actually screamed here, don’t look at me)
The fact that Stiles touched Derek’s arm in the ambulance.
The fact that Stiles hesitated before he tried to find the darach who was about to sacrifice his dad just because he saw Derek lying on the floor. He still hesitated. And from the preview for the next episodes we know he will be back for Derek, trying to wake him up.
Also, this shot.
TL;DR: EVERYTHING IS STEREK AND
NOTHING EVERYTHING HURTS