One Piece: The Elder Twin

(Previously known as Being Luffy isn't Lucky) An utterly random person comes to their senses to find out that they're being dangled by their legs, not to mention that they feel some slight vertigo. Upon realisation, they discover that they've become... ahem, I mean they share a body with the one known as Monkey D. Luffy and they also have no idea who they are themselves! The one thing they do know? They used to be an absolute loner. (EDIT: So... a few months later and I come back to this and read like a few chapters. Only to realize the absolute rubbish the story and everything has become. There was many needlessly developed things that just waste chapters and don't even develop anything. The fiction's Mary Sue was horrendously developed. I'm just repeating myself to try and convey how terrible it developed... like seriously. IF I were to update the fiction again I would be thinking of improved concepts and ways to present everything which would contradict the entire way I previously presented everything.)