You think you really know someone, and then they commit an act so shameful, so inconceivable, you're left wondering if you really knew them at all.

Stiles threw us for a major loop during tonight's episode of "Teen Wolf" when he fought off -- and murdered -- Donovan, who attacked the high school senior in a bid to get revenge on the sheriff. The criminal-turned-cannibal was on two missions: fulfill the Dread Doctors enigmatic plan (they did transform him into a wendigo, after all) and seek revenge on Sheriff Stilinski, who may be indirectly responsible for putting his ex partner (and Donovan's old man) in a wheelchair during a shootout.

"Did he tell you that he was too scared, too much of a frightened little b*tch to go in after [my dad]?" Donovan spat. "Or do scared little b*tches not tell their little b*tch sons about their failures?"

Insulting Stiles is one thing, but the super sleuth absolutely won't stand for someone trash-talking those he loves. Aaaand cue what could quite possibly be the most shocking "Teen Wolf" murder to date (er, minus Allison, obvi).

Stiles had two options, as we saw it: Run and hide, or act quickly. We can sort of understand why he acted this way -- his life was at stake, his pop's reputation was being dragged through the mud, and he's clearly not afraid. He protected himself, but it came at a hefty price. We can't be sure what it means for the rest of the season and for Stiles' relationship with Scott and Co, seeing as the life he took has clearly shaken him to the core.

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