It’s easy to assume that D. is simply Luffy’s middle initial when you’re new to “One Piece,” but then other people with a D. in their name start to appear. We meet Portgas D. Ace, Trafalgar D. Water Law, and learn about Gol D. Roger, the last Pirate King and the one who hid the legendary One Piece treasure.

Several people mention the “Will of D.,” which is a connective tissue between many of the greats in the “One Piece” world. It soon becomes clear that the Will of D. has something to do with the Void Century, a period which nobody is allowed to study under the law of the World Government. The mystery is never fully uncovered — at least, it’s yet to be. It is implied that the Will of D. is hereditary, however, and linked to a common ancestor from the Void Century.

Maybe all the D. characters are blood relatives from way back when. Or perhaps they simply all came from the same village or tribe. One thing is for sure, though: Everyone with the middle initial D. has ambition, and many have achieved great things. So who are Monkey D. Luffy’s direct relatives, then?