Selected lines from Caitlyn Siehl's magnificent poem:
When is a monster not a monster?
Oh, when you love it.
Start by pulling him out of the fire
and putting him back together
with the pieces you find on the floor.
There is so much to forgive,
but you do not know how to forget.
When is a monster not a monster?
Oh, when you are the reason it has become so mangled.
Thinking about how on OUAT Dark Hook tells Emma that she's an anchor to try to hurt her but the thing is he's right. Emma is an anchor for Hook. But anchors aren't bad things. Ships need anchors. Anchors keep ships where they're supposed to be, keep them on course, keep them in safe harbors. So of course Dark Hook would see her anchoring him as a bad thing because the only thing that he cares about is freedom at the cost of all else. Freedom taken as the highest or only good becomes the freedom to destroy yourself and others, the same way a ship without an anchor will be taken off course or drift away or smash against rocks. And that's exactly what Dark Hook's course of action is-- pure chaos, smashing himself against the rocks. Killian in his right mind would absolutely agree that Emma is his anchor, but he'd see that for what it is: she connects him to home, to his safe harbor, keeps him on his course. And he does the same for her.
AND, it's in that role that Emma eventually saves Hook from the Darkness-- it's through seeing her at the climactic moment by the lake that the anchor keeps him from being swept out to sea.