This is Stiles. He wears glasses.
Oh and he's a sex surrogate helping unknottable werewolves KNOT.
Derek is a bit too emotionally constipated due to she-who-shall-not-be-named and has intimacy issues. Not performance issues. I want to be clear about that.
So yes, Stiles is a safe place for Derek to have this particular werewolf experience and it is awesome. Were you in any doubt? However there is a stipulation - this is a one off - no further contact.
Well you know that's not going to happen. Go ahead and read, or listen,
to it to get your own happy ending ;)