We all know that Sanji’s from North Blue, though he met the crew while working at Baratie Restaurant in East Blue. We also know that Red Line divides the world in two parts, with three seas each:
1. East Blue + Grand Line (Paradise) + South Blue.
2. North Blue + Grand Line (New World) + West Blue.
From that, we can assume that there’s only 2 ways of getting to East Blue from North Blue:
1. Reverse Mountain and Calm Belt. This means, entering Grand Line from North Blue through Reverse Mountain and then exiting Grand Line through Calm Belt to East Blue. This is the “easiest” way, though there’s a high probability of dying in Reverse Mountain and even more in Calm Belt.
2. Mariejois. I don’t really have any idea on how to enter Mariejois except from scaling the Red Line at the end of Paradise or at the beggining of New World, but there must be some way to do so, reserved only to nobles or tenryuubitos and their staff (we saw Tenryuubitos and some of his servants back at Sabaody).
From my point of view, the first option is impossible. Why? Well, when the Strawhats were about to enter Grand Line, Sanji didn’t have any idea of what Reverse Mountain was, so it’s quite obvious that he hadn’t travelled through it as a kid.
The only possibility would be Mariejois then. So this gives more credibility to the theory that says that Sanji is a noble of some kind. He could have been to Mariejois as a kid with his noble family and he took advantage of the situation to escape from them, later being able to get in a cook’s ship that would bring him to East Blue. But then again, Oda always surprises, so we don’t know what he’s got prepared (could it be about to be revealed, could it have something to do with Sanji’s current “disappearance”?
There might also be a third way of getting to East Blue from North Blue, though I find it highly anticlimatic. The thing would be that one could cross Red Line in some parts of the Blues, meaning that not the whole Red Line would be a cliff as in Grand Line, but that it would rather have some places similar to beaches where ships could dock, thus being able to cross from one side to another. If this was true, though, I think One Piece would lose his characteristic “divided world” theme, which I think is the main point of the series (there’s a world divided in four pieces waiting to be reunited in one single piece).
Anyways, this is it, guys. I guess it’s not much of a theory, but instead it’s more of a punctualization that gives credibility to the theory of Sanji being a noble. Hope you liked it!
Feel free to share your thoughts on how Sanji could’ve got to East Blue as a kid.
*Theory by Jinbe