Michael is a slave suffering from Stockholm syndrome. He's addicted to his master even thought Axel has done horrible things like raping him, and torturing him with dark magic.
Axel actually has feelings for him, but he tries to hide it by hurting him. He hates himself for falling in love with a human and lets Michael suffer for it. However Michael doesn't mind being hurt as long as he gets to be close to his master. He finds comfort in the tender moments they share at night. And eventually Axel slowly begins to care for him.