I was thinking that maybe BB is Luffy's uncle. In other words: Dragon's brother, and Garp's 2nd son. It adds to the "WTF IS UP WITH THIS FAMILY" type of deal. Ha ha.
In my mind, this is how it goes:
Garp has 2 sons: Dragon and Teach.
Dragon was the "favorite", so to speak. Teach resented Dragon.
Dragon is now the leader of this super power that can rival the WG.
Teach wants to topple the delicate balance between the WG, Shichibukai, and 3 emporers to gain the attention of his brother, and show him who's boss now.
Teach may have found the most opportune moment recently to come out of the shadows: Crocodiles defeat. Since one of the Shichibukai was taken down, the balance is unstable. It may have been the perfect time for him to strike out on his own, and try to claim the seat of the next Shichibukai.
Now, so far, there is Garp, super strong guy in the WG. Dragon, an opposing force to the WG. Luffy, a strong pirate. Ace, working under one of the 4 emporers. And now Teach, the mysterious pirate.
I just thought of something.
D's in OP
the 4: Ace (indirectly)
Now, of all the world powers, the Shichibukai doesn't have a D (as far as we know). Maybe there is a big conspiracy behind the D's. Hm...Roger started this new era, and Luffy's going to bring it to an end.
Now I'm babbling. Meh, whatever