User blog comment:SaintCoke/The Eight Great Mysteries of One Piece/@comment-3199219-20101110224751

I think the first, second, third and fourth are pretty much connected somehow.

The fifth, I agree with Pandawarrior, that Sabo is alive (otherwise Oda wouldn't introduce him), but I doubt in a happy reunion.

The sixth, I don't have a clue why is that so. Maybe he was threatened, but the WG said it was his will.

Blackbeard. hmm. Marco said that he has a strange body, but I always thought that that was because of his devil fruit ability. Maybe he ate a person? :D

Luffy's mother. I have a funny theory that she might be a noble, or even a Celestial dragon. Remember that the land where Sabo, Ace and Luffy lived was full of nobles.