I think that part of why Stiles aiding in Peter's murder is so important to me is because it stands in such a contrast to Peter's behavior toward Stiles.
Peter never harmed Stiles, at all. He doesn't hurt him, the worst he does is drag him along by his collar and shove his face down onto a car but even that is done much gentler than werewolf strength could make it.
But Stiles? Stiles took the first step in Peter's murder, by throwing the first Molotov cocktail. By wanting to set the victim of a horrific fire on fire again.
It's so ruthless and vicious and it is contrasted so hard by how Peter truly goes out of his way to not harm Stiles.
Not in the hospital when Stiles realizes Peter is the Alpha. Even though Peter could have so easily killed Stiles before Derek got there, but instead Peter just stood there and smiled at Stiles.
Not on the lacrosse field when he could have janked Stiles around, forced him with threats of violence. Even though Peter had just violently and animalistically attacked Lydia, yet even the act of making Stiles get off the ground is straight-up gentle by guiding him by his chin and not hauling him up with force.
Not in the parking garage, where it would have been so easy to force the bite onto Stiles, where it would have been so easy to just kill Stiles once he fulfilled his use. Even though we see the dead nurse in his trunk, because he killed her for being no longer useful. Even though he wants to give Stiles the bite, yet he accepts the rejection. And he just... leaves, not a hair harmed on that boy.
Peter's own behavior toward Stiles already stands in stark contrast to his behavior toward literally everybody else.
And, to me, it is heightened even more by the contrast of Stiles' own ruthlessness.
Because Peter did something worse than harm Stiles. He harmed those Stiles loved. He bit Scott and he tore into Lydia.
And it's probably my favorite character trait of Stiles', his unbreakable loyalty and his ruthless defense of those he loves. And I like to think it's also Peter's favorite character trait of Stiles'.
Which makes the murder so much more fucked up, in such a delicious way. Because it was traumatic and literally deadly to Peter, but I like to think that a part of Peter appreciates the part Stiles played in it.
Peter, who killed everyone who was involved with the Hale Fire, appreciates the ruthless murderous intend Stiles feels when those he loves are harmed and wronged. Even when it's the one boy he never harmed, never wanted to harm.
And that's fucked up and twisted and delicious and perfect.
