User blog comment:HanataSanchou/Diez Drake/@comment-24769684-20160309014054

I've been pretty impressed that Oda's managed to take eleven characters, which is a lot, and make them all into relevant and interesting players in the New World, with the possible hopefully temporary exception of Killer. X Drake has interested me the most out of all the Supernovae other than Luffy and Law due to his unclear connections with Kaido. It wasn't until the anime version of the Corazon flashback rolled around that I began to appreciate how big his role really was, and this was aided by his and Barrels' backstory being revealed in Volume 78's SBS.

From the SBS, it was clear that Drake looked up to his father when he was a Marine, and from his picture as a child, he really seemed to idolize the Marines. Drake witnessed his father becoming a pirate and how it turned him into a cruel man, and suffered abuse at the hands of the father he used to look up to. It makes sense that Drake would want to join the Marines, as through his father and saw stark parallels of life as a Marine vs. life as a pirate. From what he knew, the Marines were perfect, while the life of piracy was a cancer that took his father away from him.

We don't know what happened in Drake's time in the Marines, just that he rose to Rear Admiral rank before defecting. By then, he may have seen enough of the Marines to know that they really weren't perfect as he once thought. So who knows? Maybe he decided to become a pirate to look at life from the other side, to see what morality was like from both sides of the spectrum he had spent his whole life believing in.

My conclusion from all this is that Drake is a man of morality, and he wants to find a side that is truly right. And unlike other characters, his definition of right doesn't seem to be rigid to a certain organization, allowing him to follow his feelings. One Piece is not about right vs. wrong, as Luffy has never sought to become a hero to people. He just wants to have an adventure while standing up for his own beliefs if those ever come into play. Nothing in the One Piece world is stark black or white, and it seems that Drake is trying to find the closest thing to his vision of white.

If my conclusion is correct, it doesn't really help explain why Drake is apparently allied with Kaido, and I can only think of two logical reasons for him to do so.
 * He wishes to participate in Kaido's war: Maybe Drake is tired of trying to find the right side, and shares Kaido's dream of tearing down the world, with the intention of building up his own organization that will promote his values.
 * He wishes to depose Kaido: On the other side, Drake may wish to bring Kaido down for some reason or another, though there's not really any reasons I could point to or logically speculate as to why he wants to do that right now.