It's Not My Fault We're Still Friends With Our Bully From School...

So there was this kid in my grade back in elementary school, let's call him Kyle, who used to be the biggest bully around. Made us feel small constantly. One day he just stopped for no reason and became friendly. I mean, really friendly, invited me over his house after school one day... We've been friends ever since but it always feels weird to others because of how we started. Sometimes I wonder what made him change that much but don't ask directly out of fear it'll bring back the old memories. It's not my fault people think we should still be at odds though....