This is a theory I have been working on since chapter 801 came out and I find really interesting. It is about Sanji somehow being Satan or Oda being inspired by Satan. Moreover I will talk about Sanji’s family, his will and his relationship with Kaido!
Reasons why I believe Sanji is the “Satan” of One Piece/or his characteristics are inspired from Satan.
It is a widely known fact that Satan in his animal state/version is a billy goat.
Billy goats’ horns are spiral just like Sanji’s eyebrows. Moreover in some pictures and movies Satan is depicted with curly eyebrows just like Sanji. Still not convinced?Then what about this: Satan is the lord of hell-a place filled with fire right? Sanji’s diable jump is composed of fire and after the timeskip Sanji also has a new technique called Hell’s Memories. I believe Oda had been trying to foreshadow Sanji’s connection to hell. Some other facts that can be Oda foreshadowing what I said are: Sanji turning to Devil at Thriller Bark (although it is for fun reasons).
There second foreshadow is Sanji being a cook. Yeah Sanji being a cook has a lot to do with fire. He has been seen using fire while cooking just like every cook and that’s why I think Oda did not make Sanji “Satan” since the beginning of the series but realised afterwards that his character/appearance would be really suitable for the role.
Moving on to the second part of this theory/speculation I am going to talk about Sanji’s Will and its former owner. Furthermore,I will talk about Sanji’s family. If Sanji really does resemble Satan , I firmly believe that he is the son of a Tenryubito. To be more specific,I believe that when the Tenryubito saw Sanji’s eyebrows (some months after being born cause babys’ heads are not completely formed when they are born)and maybe a tendency of him liking fire and approaching it , they understood/thought it was a sign from above. As most of us know, Satan protested against God and is said to have fought with him. So what the Celestial Dragons actually thought was that Sanji was going to destroy them as they are considered Gods-they thought he was a threat. Actually I believe he inherited Don Quixote Homing’s (Doffy’s father)will.
Just like Homing, Sanji would grow sick and tired of the Celestial Dragons and would punish them in a way more brutal way than Homing did (he actually did not have enough power to ruin the Celestial Dragons,but Sanji did!). So they CD wanted to kill Sanji desperately. This is the point where Sanji and Kaido are connected.
Sanji’s And Kaido’s Relationship
There is a big chance of Kaido having been a slave for the CD.I believe it too. So what actually connects Sanji and Kaido is this: Kaido overhearring that the CD wanted to kill Sanji, they hated him and they called him Devil. Think of it! Kaido actually SAW HIMSELF IN SANJI. He has obviously been wanted dead by a lot of people, hated and called the Devil too. Then Fisher Tiger arrives at Mariejoa’s setting everyone free , along with Kaido taking the little “Satan” with him before him being executed. But Kaido would never be a fitting parent right? So what I believe is that he left Sanji at someone he trusted and never saw him again. But he cared so much for Sanji. However the sea is huge and Sanji hasn’t always been at the same ship nor at the same location. So Kaido has been looking for his lost “self” and that’s why he is depressed and wants to die! Because he can’t find the only creature that actually made him happy and did not make him seem like a brutal freak!
Other Thoughts: I believe Sanji will awaken CoC as the King of hell. And now something about Sanji’s character. Although it may seem crazy, Sanji being okay with being friend-zoned is like Baby-5’s character. I think that at the very depth of his mind he has memories (filled with “fog” and can’t really recall clearly) of being wanted dead and that’s why he is just okay with everything. That’s also why he respected and loved Zeff so much… because his is one of the few people that risked their life for Sanji!
*Theory by Usopp Haoshoku Haki