CAS HAS TO. SOMETIMES THE BODY BREAKS DOWN and Cas is the only one who can fix it, and at first Cas didn't really realize he was doing anything wrong with adding these new modifications. But then as he starts to get to know Dean, he starts to feel a little guilty about them, but TOO LATE NOW. DEAN WILL LEARN OF IT IN SOME PLOT TWIST IN THE SEASON FINALE and there are gonna be so many mantears.

IN ONE EPISODE, DEAN GETS A COMPUTER VIRUS. For porn adware. You should see the Director's Cut, man.