Lel this topic is interesting, but the discussion turns bitter XD
We'll have another interesting plot twist. Say, Luffy grows up being a hyperactive marine, still goofy around and such, but as he's so trusting, he believes everything what Garp tells him about the bad side of the pirates and strives to become a fleet admiral (his motto maybe sounds like justice will prevail or whatever holds the key to nondiscrimination. He may as well thrill to the idea of getting food from islanders if he saves them from pirate attacks (or it can be reversed though).
However soon enough he met Ace, his sworn brother before they got separated by Garp when he was a kid, and surprised to see the latter being a pirate. Luffy ofc questioned Ace's choice of lifestyle, but Ace's explanation baffles him and makes him doubtful with his own career instead (possibly has something to do with Sabo's death because of WG selfishness, anything). As a marine from HQ, he travels island to island, looking for troublesome pirates and save people.
Through that he learns another side of truth; pirates' dreams, WG's true nature. Even if he doesn't understand it quite well, his crew; nakama are there to share the responsibility. Pretty much similar to Smoker or Kuzan, but replaced with Luffy's personae. The problem is Luffy's dad and Sabo (turns out he's still alive) are part of RA, while Ace is a wanted pirate, so his family aside Garp won't hold back to fight him if WG intend to stop 'em. They've promised to watch out for each other, and they're struggling to it keep up. Akainu appears, and threatened Luffy to choose between peace or injustice, perhaps secretly having other vicious unlawful party like Blackbeard to kill Ace or Sabo or both to cause Luffy hating pirates. Since then Luffy vows to catch every pirate there is, including his family member, for their own good and others...
.....somehow it evolves into a tragical one... well... Am not good with this kinda stuff.
