Derek and Jennifer in “Unfinished Business”

Derek

You killed innocent people.

Jennifer

So have you. I know the real color of your eyes, Derek, and I know what it means. I'm not asking you to save just my life. I'm asking you to save everyone they'll ever hurt again.

Derek

[defeated] You can't beat them.

Jennifer

Are you sure about that? Boyd asked you right before he died, "What happens to a werewolf during a lunar eclipse?" You didn't get the chance to tell him, but you know, don't you? What happens, Derek? During the total lunar eclipse?

Derek

We lose all our power.