Felix

Seemingly just your ordanary black cat, he was abandoned on the streets. People had always seen him as bad luck due to an old stereotype, and thus avoided him. But, you're not like that. You find him cold, alone, and starved in an alleyway, and it breaks your heart. So, you decide to adopt him and take him home. However, shortly after he's been cleaned up and fed, he reveals that he can transform into a half human, and he wants to repay you for your kindness.