Blood

(Dean) Why you letting mommy dearest tie you into knots?

(Crowley) Because we're family. We’re blood.

(Dean) That's not the same thing. A wise man once told me, “family don't end in blood”. But it doesn't start there, either. Family cares about you, not what you can do for them. Family's there, through the good, bad... all of it. They got your back, even when it hurts. That's family. That sound like your mother?

In Supernatural, Season 10, Episode 7, “Inside Man”