I had a two year break from a grade-school bully when we went off to different middle-schools.
I saw him again in high school. To my surprise, he was happy to see me and insisted we were friends.
I reminded him about how he tormented me, and teased me, and took things from me. He had none of it and insisted we were buddies.
It was disconcerting, but I reluctantly relented and hung out with him a bit. He was eager to please for sure.
Then one day we went to his house and he revealed to me that his father had died, older sister was on drugs, and his mom was a raging alcoholic. I saw the mom in action – it wasn’t pretty. He was really lonely and pretty desperate.
He never did admit to being a bully, but I continued to be friendly with him through high school.
He, ultimately turned out to be a good guy, got married, had kids, became a nurse.