As One Piece enters its final saga, the number of mysteries that remain will slowly begin to be resolved. Fans have always come up with their own theories and speculations, but Eiichiro Oda loves to mess with expectations, always remaining unpredictable in the process. The mysterious Monkey D. Dragon has remained an enigmatic figure since his introduction all the way back in the Loguetown Arc, nearly two decades ago.
Being the most wanted man in One Piece, leader of the Revolutionary Army, son of the legendary Marine hero, Garp, and on top of all of that, the father of Monkey D Luffy, the series' protagonist. While Dragon is a legend in his own right, the audience barely knows anything about him. His history, his relationship with Garp, his nonexistent relationship with Luffy, and so much more have yet to be elaborated on, but there are some details in his character design that can possibly provide some clues about his background.
The most striking thing about Dragon's character design is the tattoo on his face. An X-shaped pattern crisscrosses the left side of his face, with an interesting red and black color scheme. Tattoos such as this have only ever been shown in one group of people: the Skypeians.
The Skypeians are the indigenous tribe that live on the sky island of Skypeia. Their culture and designs are obvious references to real life indigenous tribes, and the markings on their skin are no exception. The fact that Dragon shares the same tattoos as they do is no mistake, but what exactly it means is up to interpretation for the time being.
It's unlikely that Dragon was born in Skypeia, simply due to the fact that Garp, his father, would have had no reason to go to Skypeia. Unless Garp married and had a child with a Skypeian woman, it's more likely that Dragon went there some time in his youth and was integrated into the tribe in some way, receiving his tattoo as a result. If the tattoos are indeed of Skypeian origin, they could help explain another mystery that surrounds Dragon: whether he possesses a devil fruit.
When Luffy was about to be executed in Loguetown by Buggy, a lightning bolt struck the stand he was being held on. Later, when Luffy was apprehended by Smoker, a blistering wind began, right as Dragon touched Smoker's shoulder to get him to release Luffy. Neither of these things can be coincidences, and yet Dragon hasn't been seen with these mysterious abilities ever since.
If Dragon does possess a fruit, combined with the indigenous symbolism on his face, it's possible that Dragon is the user of the mythical zoan devil fruit, the Tori-Tori no Mi, Model: Thunderbird. The Thunderbird is a spiritual bird in North American indigenous mythology that is said to have the ability to control powerful storms, lightning, and thunder.
In Algonquin iconography, the thunderbird is depicted as an X-shape, with its body in the shape of an X, and the wings and head facing out to the side. Dragon's supposed abilities, and their similarities to the powers of the mythological creature make this connection all but certain.
The Thunderbird is also said to fight against the creatures of the underworld, specifically the great horned serpent, to protect the people of the world. The thunderbird is also said to be an enforcer of morality, punishing wrongdoers with impunity.
The Revolutionary Army is dedicated to fighting back against the Celestial Dragons, the nobles that control the events of the world. The Celestial Dragons could easily be the interpretation of the great horned serpent in the myth, neatly tying the connection between the Dragon and the thunderbird together.
While it's unlikely that Dragon actually came from Skypeia, he seems to have at least some connection to the land above the clouds. The tattoos, general motifs in his character design, and his abilities all point towards this fact. His hinted at devil fruit could also turn out to be something completely unexpected. Fans have already waited twenty years to see what Dragon can do, a few more years won't hurt.