"Prongslet... that's a very serious vow, you shouldn’t be making those for the sake of making one. Are you sure I’ll need it?" Harry nodded, and the weight of the situation seemed to set like a rock in Sirius stomach. Sirius made a vow much like Snape had made and Harry made a vow of honesty and told him the bare minimum, that Dumbledore is using him, and that no matter what Sirius does Dumbledore will do anything to keep him under his thumb, to keep him with the Dursleys.