A werewolf's anchor is that which they can concentrate on to keep themselves human.

[[Allison Argent|Allison]] is [[Scott McCall|Scott]]'s anchor, because thinking about her and hearing her voice helps him fight the [[Werewolf+bloodlust|bloodlust]].

[[Derek Hale|Derek]] claims that his anchor is anger, presumably his pain over the death of his family.

Isaac's anchor is [[Mr. Lahey|his father]], who wasn't always the abusive man he became.