There was this girl in my school who was an immigrant and didn't speak the national language. It was, I believe, second grade. Our whole class, including me, constantly laughed at her, and it was clear she wasn't enjoying it. She was somewhat of an outsider, never participating in social events, never properly socializing. I left that school the next year, so I didn't get to see her anymore.

I met her again in high school, six years later. She spoke the national language, integrated properly, and had many friends. I even met her through a mutual friend. We spoke normally at first, simply acknowledging our shared past, but some guilt gnawed at me. It's not like I couldn't sleep thinking about how I treated her, but I couldn't just pretend I've always been nice to her. So, one day, I took her to the side... and apologized. She was flustered, she clearly didn't expect that, nor did she hold a grudge according to her, but I felt way better afterwards.

Edit: spelling