House Elves and Homework

For one of my classes, we had to define "personhood" and the consequences for ethical decision making. It got me thinking about House Elves (largely to amuse myself and keep from getting too annoyed).

Kant defines personhood when self-conscious, rational entities are capable of blaming and praising, and can act as moral agents.

By this definition, I think centaurs and goblins are persons. They just do not subscribe to the same moral rules as humans. But what about house elves? They are self-conscious, rational and capable of blaming and praising. But due to the magical contract they have with humans, are they fully capable of acting as moral agents? Dobby certainly seemed to fulfill this definition. So did Winky and Kreacher. They did what they thought was right. But they did these things within the context of concern for betrayal and the 'threat' of an order. Under order, are house elves completely incapable of acting as moral agents? For example, does Kreacher's passive resistance to Harry's orders constitute action as a moral agent?

Discuss. . .