Diana: What is the covenant?
Marthe: You really don't know. it forbids interspecies relationships.
Diana: That's insane. Why would anyone ever agree to that?
Marthe: There were a lot more of us creatures back then, and we'd grown accustomed to taking what we wanted. Phillipe decided that if creatures from different species mated, it might upset the balance of power. So, the Covenant was drawn up.
Diana: What happens whenever creatures break it?
Marthe: To my knowledge, it has never been broken.