In this fanfic Luffy doesn't have a devil fruit he Insted trains in haki
Luffy in the bar with shanks and his crew were spending time chilling then suddenly bandit came but unlike in the original timeline this time shanks didn't resist their mocking he simply knock them with conquerors haki
Luffy was amazed to see that the bandit were knock down so easily without lifting a finger
Luffy curiously asked to shanks did u do that how did u do it plzz teach to me Luffy asked shanks to teach him that power and shanks told him about haki and Luffy was amazed to hear that there were such things in this world
And he decided to train on haki and be the pirate king without using any devil fruit
And many year passed and in that one year he trained with garp about telling garp about haki garp saw a spark of determination and Luffy eyes and decided to train Luffy on haki
And after sometime garp realized that Luffy has vast potential in haki so he teaches Luffy haki
Now the time to set sail had come and Luffy finally embarks on his journey..