Oda hinted Blackbeard’s possible origin 800+ chapters ago back in the Drum Island Arc. Let me explain.
Oda drew Blackbeard as a kid, who’s shown to be crying at NIGHT with a half moon in the background. The crazy part is, there’s a piece of SNOW under his feet.
Snow? And why is this has to do with snow?
Well, let’s go back to the time where the named “Blackbeard” was ever FIRST mentioned in the manga. It was in Drum Island Arc (a very snowy place).
In chapter 133 , Dalton said that Blackbeard Pirates went and destroyed Drum Island in a blink of an eye.
Next chapter later (134), Luffy brought up an interesting topic to Sanji that there was a guy from a bar who told him that there are people who live in snowy countries that don’t sleep. Because if they do, they’ll die.
Oda is a genius in storytelling!
*Theory by brikskohuh