My older brother's best friend Lance has been there for us during hardships. He's like a family to us. His major is child psychology and has participated in animal shelters too. However, I was shocked to find out how their friendship started. Both are now 24 year-olds.
I overheard a conversation that Lance was really a total jerk in middle school years and freshman year of HS. He targeted my brother, forcing him to do his homeworks or else a fight; shoplifted, a total rotten person. My brother got into a huge physical fight with him sometime in 9th grade. He had enough and both ended up with bruises and a busted lip. It was an even match. Both got suspended for a week or so. Ironically he didn't hate my brother afterwards. He even thought it was deserved. My brother was admired and respected since.
Needless to say I was shock. That was the end to that rivalry, end to the guy's old ways. Everyone was talking about it at school for a while. How do guys do that? You just fought the other dude, it's a epic moment and yet you befriend him afterwards. How?
Personally I can't imagine ever being friends with another girl I just fought with or if she beats me. Nope.