Since we have no explicit plans for how long we've been together, I vote we got together basically just meeting up and picking up people and have been as a group for a while, to do a few missions, and everyone is aware of our "less-than-legal" missions, but haven't done much together, so we know each other enough to have a basic relying trust, but if it came down to it, none of us would necessarily felt beholden to the others...
In other words the basic relationships are there and they can grow or be destroyed fairly easily...