Devon was the most dangerous female pirate ever to be imprisoned in Impel Down within the entire age of pirates. She is called “Crescent Moon Hunter” which I found to be quite interesting.
We know that the Kozuki clan is heavily associated with the crescent moon. We also know that Wano Samurai have made their way on the outside, and are the very least known to the outside world.
Oden was a Wano Samurai who became a pirate, and Zoro village was founded by Wano Samurai. This leads me to believe that when Kaido killed Oden, unknown Kozuki clan members went out to see in search of help to deal with Kaido. Most of the ones who did end up dead and in particular, those who were women became famous on the seas, for being killed by Devon.
As to why she did this, I do not know. She seems to revel in killing a beautiful woman. She is obsessed with collecting beautiful women’s heads and was once the worst female criminal within the Golden Age of Piracy.
We know that Devon identifies as a woman, but hates women, has a character design made to look unattractive, and has eaten the Inu Inu no Mi, Model: Kyubi no Kitsune, a Mythical Zoan-type Devil Fruit that allows her to transform into a nine-tailed fox.
Yamato identifies as Oden who is a man, has a character design made to look attractive, and has eaten te the Inu Inu no Mi, Model: Okuchi no Makami, a Mythical Zoan-type Devil Fruit that allows her to transform into a divine wolf, as well as a human-divine wolf hybrid. Also likely to have an arc where end up fully identifying as a woman again.
Now let’s talk about their devil fruits, as we know they are the first two-woman mythical zoan devil fruit users.
Amaterasu(a named attack in both One Piece and Naruto) is the goddess of the sun in Japanese mythology. However, there is a video game called Okami(popular in Japan) where Amaterasu is a white wolf-like Yamato. In this game, Okami is the protagonist and is thought to be a familiar of Orochi (the name sounds familiar)
Now I’m not going into detail with this game, but there is a tribe called the moon tribe, and we know in One Piece that 5 of the 6 known samurai clans are associated with the moon.
In this game Okami there is a character called the Ninetails a large, powerful, nine-tailed kitsune who rules Oni Island (Yamato Race) and is one of the major antagonists in the series. This leads me to believe that where ever the other members of the Yamato race are located the Blackbeard Pirates will cause some mayhem there.
Nine-Tailed Foxes were originally evil but later turned to be divine beasts and the signs of good fortunes in China before the legends were spread among other Asian nations (India, China, Korea, Vietnam, Japan) and evil characteristics, most notably transforming into beautiful women and troubling nations were added.
*Theory by UmdAvatarFan