After the fight against Katakuri,Luffy finds himself in another world,his wounds completely healed. The first thing that Luffy thinks after coming to another world(which he doesn't know yet)is food. But instead he finds a woman with long pointed ears trying to save two children. Luffy's new adventure in another world starts.

Second Volume of Another World Series of One Piece.

What if shanks and luffy time traveled to the past after everyone is dead? What if shanks somehow became a devil fruit user in the future by accident just by touching it? What if the devil fruit was special and chooses who will use itself? What if it choose shanks for a reason? What if shanks didn't have the same disability that other devil fruit users had? What if shanks can still swim? What If because of the devil fruit shanks had, the elements would protect him and those that shanks views as friends and family? What if this devil fruit can sense what shanks needs and make it happen? And then time travel became possible only because of shanks and he wakes up on his old ship that is at dawn island? Then shanks goes to the bar to see luffy. Then they both watch and study each other carefully to see if each other were the same from the future? (Yep my way, probably different everything including personalities. )