Hmm... I'll have to say the first duel missions will go off without too much trouble, everyone will be busy dealing with threats and trying to work together. Once the job(s) are done and everyone is setting up in the base the first signs of dissent will emerge as the varied personalities begin to mingle and clash. Without any actual job everyone will start to test each other, then our demon ally will direct us with one of two things. Either he will give us a job and we'll go out and do it grumbling the entire time, or he'll give us several jobs. If the latter than the party will implode as everyone has different thoughts regarding the various jobs and we'll either fraction into several smaller teams who happen to live nearby (i.e. same base) or establish a chain of command, likely through a mixture of rule of the strong and a few clever back stabs.