Some kids I knew that had bullied me in grade school (which were typically jock on nerd ego trips) mellowed out in their later teens and were not at all unpleasant to meet. I knew only one grim exception and maybe he’s in prison now for all I know.
I remember once in grade school when a kid who had been bullying me, TOLD OFF a group of other kids who were giving me a hard time, and he never bullied me again. I do not know what led to the change of heart from bully to hero and I did not ask — but it’s not impossible.
At 9 years old I was in a French boarding school for four months while my Dad’s battleship cruised Scandinavia and the Mediterranean with a shipfull of midshipmen. The first night, while the dorm mistress was out of the room, a couple of girls jumped on my bed, broke my doll and shredded my little diary. I didn’t speak any French -yet- so nothing came of it.