All demons know that the best way to get at a hunter is through friends. Family. People that the hunters care about.
(Hunters know this too; it's why so few of them have friends, at least ones that aren't themselves hunters.)
A lot of demons also know that the Winchesters (back before they knew their role in the way the world ends) were damn sloppy. They left people. Trails.
The woman I take doesn't stand a chance against me, but that doesn't really matter because she isn't the important one. It's her daughter -- Cassie, once Dean's girlfriend, now left to her own meager defenses -- that I care about.
My sister is off to find Dean, to dangle the knowledge of Cassie's fate before him. There's no way he can save her; he and his brother are too entangled with more important things. This will just be another quiet wound among many, another stain on his tarred conscience. But knowing him, he'll probably try anyway. He'll just be too late.
I come for Cassie. She raises a shotgun -- against her very mother! ungrateful child -- and I laugh, because bullets can't stop me.
But she doesn't falter. "I know," she says grimly, and steps forward.
Her next words aren't English; and I have half a moment to realize what she is doing before the exorcism rips me away.