there are two times in wich I remember being "in fights". I was never one of the "main" fighters though, and what I mostly did was hold the guy that was attacking by hugging them tightly. I'm big, and heavy, and my hugs are very... "absorbing".
The first time, some kind wanted to fight one of my best friends (wich is something pretty stupid to do, he is one of the strongest people I know). The rest of kinds at school started yelling "fight! fight!" and soon most kids were forming a circle around this guy and my friend. He punched my friend, my friend punched back and, as he is pretty strong, the guy took some steps backwards. In that moment, I hugged him from behind and raised him from the ground. I kept him there, screaming and trying to kick me, withy my friend mocking him, until all the kids started to laugh at him. He was so humiliated he decided to leave when I left him back on the ground. (it also helped that the rest of my group of friends was there to back my friend up... and even if we were the "weird/nerd" group, we were seven and he was just one.
The second time was just a few weeks ago. I was with some friends on the street, pretty late. We suddenly hear a soft crash. A car, driven by two preppy girls, had touched a motorcicle with a guy and his girlfriend on it. The motorcicle had fallen on the ground, and the girl felt pain on her leg.
As some of my friends went to help the girl, the boyfriend, a drunk and probably drugged idiot, started kicking and punching at the stopped car, telling the two girls he'd kill them. Some of us went to stop him, and we tried to stop him from opening the car door. He was pretty muscular and tall, and it looked like he could break those little girls with not much effort.
I hugged him from behind, and managed to have him stop after several tries. My back and arms hurt for some days, but I felt strong for the first time in years.
And that's most of my fighting life. Thank god, because I'm in such a bad shape everybody and their dog could probably beat me. But, luckly, I'm an easy-going, easily liked person and in fight scenarios I'm usually "the voice of reason", telling people to calm down.