What's the biggest multi-group brawl you've encountered?
It's always fun when you get in a fight when some third party joins the fun, but what about fourth parties? Fifth parties? More?
Biggest fight I've seen so far took place at the area just in front of the Farragut West metro station. I had been there before while working on the main quest, but had deliberately avoided triggering both the random spawn on the ramp and the mutants just acoss the river. So I decided that it was time to go harvest some Raider armor and weapons and get the mutants going. Triggering the ramp spawn point netted me some Outcasts walking down, and they proceeded to open fire on the Raider standing on the ledge above the quay. Joy! I love having those guys hang out there. I then turned around and hit the mutant activation area. A lovely three-way battle with no one shooting at me breaks out.
But wait! That's not all! From the safety of my "foxhole" (the steps of the station) I notice that some raiders are running up from the South. Turns out it was the Outcasts vs. Raiders encounter. Double joy!
At about this time I hear a couple of explosions from somewhere off to my left, and another Raider comes sprinting down the ramp being chased by two Enclave soldiers and an officer. So now I had Raiders, Raiders, Raiders, mutants, Outcasts and Enclave duking it out right in front of me. Made me wish I had some popcorn. And a minute later, while the battle was winding down, another Enclave patrol sauntered down the ramp and finished off the surviving Outcast and mutant. And then I killed the Enclave guys.
There you have it. A seven-way battle that I didn't even have to get involved in until there were just three Enclave left. The loot was very nice.
Jesus Christ! Never, ever have I seen anything more than a 3 faction duke-out. Super Mutants vs. Raiders vs. Talon Company somewhere near Georgetown/Dupont. And yeah, it was after popping out of a Metro gate. And yeah, I joined in. Fun, fun, fun 'til her daddy took the T-Bird away!
That random spawn point on the ramp near Farragut makes it really easy to get a multi-way spawn/raider/mutant battle going there. The other guys joining in was just luck.
Another good spot is at the big raider encampment along the route that Dad takes if you follow him to Rivet City. With some work you can sometimes get the random spawn from the metro across the street to mix it up with you/Dad/raiders. I've never tried yet, but after the Enclave shows up I bet you could also get the soldiers from near the library to follow you there. Or maybe the Talon mercenaries from south of the library. That one also has the added benefit of the big car pileup that goes BOOM.
I once had a fight going between Raiders, Outcasts, and Enclave going. It was great. I noticed that the Outcasts were walking towards one of the Raider farms so I followed them to watch it. The outcasts opened fire with their minigun and lasers at charging raiders when all of the sudden heavy incinerator fire rained down behind the outcasts and they got flanked and killed by both parties. Enclave won that one.