Edward Kenway comes from, and no doubt sires, a long line of loners. Even Ezio became a little less cheery in his later years. In the latest Assassin's Creed IV: Black Flag trailer, we see some of that attitude come through.
Sure, Edward does have his crew, but the man looks out for himself. He wants to make it big, like any pirate, and the video kind of suggests this leads Edward down a bad path. Well, worse than being a pirate, I guess. Eventually, something goes awry, likely involving this crazy treasure stash he's dreaming about, and he winds up allying with Assassins. Doesn't seem to care much for them, but hey, these Assassin people seem to at least know what they're doing.
Assassin's Creed IV: Black Flag comes out October 29 for PC and current-gen consoles. It will be out in November for the next-gen machines.
Edward Kenway story trailer - YouTube