Moreover, it gives Harry plenty of time to work out some of the details of his plans. What a crazy world it is, when defeating Voldemort is the secondary objective. When he thinks about all these plans, the things he wants to accomplish, he can feel the gilded thread of the Unbreakable Vow tugging on his heart. No doubt Corvin can feel it too based on the momentarily discomfited look on his face in those instances. Interesting.