This was really unsettling. Told from Isaac's perspective, it gives his insight into Stiles and Derek's relationship. And it's not pretty. It's dark.
Not that spoilerish, but I figure it's better to put it in tags:
And this is a spoiler:
The last line of the story, just about killed me:
I didn't enjoy the story, but it made me think. And feel.
Objectively, the rating should be higher, but I just don't want to do it.