Know thy players. Your players might be much better at player-driven games than myself or my players.
Yeah that helps, but this particular game I had never met half the group. Our last campaign only had 4 people and then this time a couple of them invited friends I hadnt played with before and 1 guy came in from meetup.com .
Already, your players were doing a better job than my group. They were an organized group of friends. I don't know if they started that way, or they RP'ed becoming friends, but this is better than 5 or so people with no real reason to hang out. You've already avoided a barrier my group often runs into, possibly without even realizing it.
Yeah I use the mercenary thing fairly often. The first adventure is either your last on the contract with the group or they just got out the last adventure and mustered out at the same time. I wish they had RP'ed it out a little but it was basically "you guys have all fought together through a huge war for the last few years, decide among yourselves how well you know or like each other but at the bare minimum you have all been passing each other in a camp the size of a small highschool for a couple years so you've chatted before and watched each others backs in battles before.
Writing in a background tie like this has helped me a lot since I started using it. I always try to make it very broad though so the players dont have to act like blood brothers or anything. This particular mercenary group had about 300 people left at the end of the war so there was plenty of room for each person to have had their own niche in it and social circles.
(It's not like I don't notice this problem as a player. We played an Exalted game - one where one PC wanted to do nothing but breed yaks. I was playing an assassin. Unfortunately, we'd not collaborated on character generation, so we were ye olde sociopathic strangers. I decided to wait until I saw other PCs before introducing mine on the email list. One player wanted to be a general, so I saw him as the group leader, and my PC would work for him as a spy and assassin, rather than be a "lone ranger" with no ties to the group like the other PCs. I tried to find connections to other PCs but couldn't find anything. Unfortunately, no one else seemed interested in the general's "conquer the world" plot, except after noticing we'd wasted 5 hours of a 6 hour session, at which point all the PCs would get together for a battle royale. Still, now the two of us didn't have to compete with each other for DM time. And then the player moved out of town. The next player I attached myself to also had to move out of town. It was like a curse.)
I've only been in a few exalted games but I dont think your experience is unusual for them, unfortunately.
The PCs decided to do things as a group. That's very helpful. We had a Warhammer FRPG campaign like that, where we managed to decide things as a group, but realistically only because two players (out of six) were actually writing the plot. The rest just went along. Not that I saw "going along" as a bad thing, and my own PC was just "going along". It was better than having six plots. I guess that was player-driver, but not players-driven.
Kinda. The mercenary captain pulled all the officers together (they were junior officers) and laid out his idea that the company should take this town over and rule it together instead of disbanding and all heading in opposite directions and then asked who was with him. They did ask some questions and one guy gave a speech of his own so they had input for sure and could have walked in another direction and I would have let them but the original campaign story was set by my NPC.