It depends on a huge number of factors really. Anecdote time :lol:
A good few years ago, I was out in town with my reenactment friends. We're a bit of a mixed bunch really; one of us works for the RAF, but when he goes out he looks like a traveller; another is in the Navy and built like a brick ****; the rest of us a gaggle of biker/rocker types and our other halves. I think there were ten of us in total on this occasion and some block and his mate banged into my RAF/traveller mate.
It was the usual deliberate walk into him, then have a go for getting in his way kind of thing. He started calling him a smelly bastard and stuff.
We all just looked at each other and laughed and agreed. In that situation, to fight would have been ludicrous. The guy kept trying to provoke us, but there are ten of us, and more than half of us spend each weekend fighting side by side. There's this one guy and his mate looking a bit worried, and the trouble you'd get in for being involved in a fight like that (which would have no doubt ended very badly for this one bloke) wasn't worth it. So we walked off. I guess it's flight, but with the confidence in the group, fight just wasn't needed.
A year or so later, same group and a similar situation. About five of us were sat in the pub, and the Navy guy was approached by somebody. It became rapidly clear that it was a "bully" from his school days. Sam was obviously uncomfortable and this "bully" started to wind him up, using typical bully tricks of psychological intimidation. Sam wasn't having any of it though, and this guy got completely wound up and threatened to "plant" Sam. Sam suggested it would be a bad idea. When the bully said "yeah, and who's going to stop me?", Sam pointed behind him, where three of us had stood up surrounding him. In that case, fight would have been an option and we kept close to Sam as we went home in case this guy wanted to pick him off.
It's odd though, as I wouldn't try anything against Sam, as I say, he's built like a brick **** house, proper, seriously huge.
Both these times, I was pretty fit though. Exercising or fighting regularly which makes a huge difference in confidence.
People will remember the queue for the Skyride at Alton one CF-Live where some queue jumpers wanted to beat me up for arguing with them. I didn't back down, but I certainly made sure I was backed up afterwards. Three against one when I was fat and unfit is bad odds. I'll stand up for myself, but I always try to handle things cleverly.
I did once throw a guy against a phone box for calling my girlfriend a bitch (she was on the phone at the time and this guy wanted to use it). He'd been yelling while she was on the phone and getting mad about something. One of the few times I can remember losing my temper and striking out at somebody.
Yeah, so it really depends on the situation and how confident I'm feeling with myself. I'll make a concious decision each time, but I'd certainly back down if a friend is in trouble unless the odds were really bad (in which case I'd help him get away).