I think the mc still loves that old man, he left the tattoo there?!?!?

no he didn't love the old man romantically, he loved him as a father figure. mc was groomed though so he thought he would be okay with all the sexual things done to him when in reality he wasn't. also keeping the tattoo was his first choice, he finally had free will to decide what he wanted to do.

Im prtty much wrote my comment in a whim. But wow! You perfectly did sum up the meaning!