This is based on a theory I’ve had brewing in my head for a while now, and the main reason I feel like posting about it now is that I’ve recently reread the Skypiea arc over the past few days. I’m going to list some of my rationale regarding why I think Katakuri has a connection to the sky. I particularly believe he is descended from the Shandians or a similar tribe, for reasons I’ll explain:
His mastery of Observation Haki
The concept of Observation Haki was introduced all the way back in the Skypiea arc, years before it became commonplace in the story. The way it’s described by Enel is as if he can hear the voices of every person who trespasses onto his territory of Fairy Vearth. He is also capable of reading the minds of his opponents and blocking attacks in response, such as when he grabs Luffy’s fists when he attempts to use Gatling (though he seems to be less proficient in that aspect because of his Logia type ability, making him invincible under most circumstances). Katakuri is one of the great pirates of the New World, and his main claim to fame is his ability to see brief glimpses of the future, and the way he uses this ability is very similar to the priests of Skypiea, dodging and intercepting attacks when he sees them coming.
Residents of Sky Island seem to have a natural affinity for Observation, so if Katakuri is, in fact, Shandian it would explain how he has the level of affinity that isn’t typical of humans.
This is the main reason I think Katakuri is Shandian specifically. Looking at Wiper’s, Calgara’s, and now Katakuri’s, there’s a distinct similarity.
Katakuri also has a wing printed on his back, which I think is a major sign of his origin while also representing his status as a half-breed. The wing also resembles the Shandians’, pointing upwards.
The lack of Sky representation in Totland
Something odd about Totland is that there aren’t any people from the sky. With the Big Mom Pirates being a Yonko crew with a very far reach, I doubt Big Mom wouldn’t know about them and how people live on clouds. What with how much Big Mom loves exotic animals and races, there’s no way she wouldn’t take interest in the Sky Islands, especially because of how strange the wildlife there is. This makes me think of two possibilities, A, Big Mom doesn’t know, B, She does and they actually live on a Sky Island directly above Totland that we haven’t seen, or C, the only one is a half-breed, being Katakuri.
This brings up the question as to why Katakuri doesn’t have wings. My idea is that it’s an effect of him being half human, and the one wing is there to represent his origin.
Thematic similarities to Enel
This is mostly just a small list of traits they share
1) Both wield a trident
2) Katakuri’s ability is a direct compliment to Luffy’s, kind of like how Luffy’s is a counter to Enel’s.
3) Mastery of CoO/Mantra (already mentioned)
4) Logia or Logia-esque ability
Regarding the circumstances of Katakuri’s birth, my guess is that Big Mom went up to Shandia at some point in her very early career as a pirate, got busy with some powerful warrior, and later had Katakuri, Oven, and Daifuku. Oven and Daifuku kind of poke a couple holes into my theory, but we don’t know enough for them to actually disprove it.
*Theory by Ganmorg