One person will have to be a bad guy. I do not like the idea of passing the character around...cause everyone is going to be a bit bias towards their own individual character. And the bad guy can't be in several different places at once, with several different mindsets. We can't all read each other's minds and know what the bad guy is supposed to be feeling or planning in according with their own individual opinions or views. It is easier to have one solid person playing the bad guy to keep everything in order.