Rimuru didn't know why, but Michael was different from everyone in this world. Even before his deah, he didn't fell this. He didn't attack him when they first encountered.

His obsession grew over time after the man, he even had his own nation now, he was powerful as ever. He wasn’t the same old slime Michael knew. He had his human form now.

He will protect him with all his might, and hope the one who had chosen him doesn't leave. He won't, right? Right? Rimuru wouldn't let him.