Akainu is pissed off guy at pirates, and he is angry at dragon. This is his character
Smoker is first to see Roger in Luffy. He understands Roger in way that Akainu cannot. Akainu only see Luffy as dragons son
Akainu has history with dragon, but Luffy is not dragon. Luffy is like Roger and Smoker hunts Luffy because he see that he will be like Roger and he will make it a mission to stop it. This is why smoker is after Luffy from beginning of grand line
Akainu only fight Luffy because of hate with dragon , that’s his motivation, so there is no deep character conflict with Luffy who has nothing in common with dragon
Smoker hunts Luffy for being the new Roger, and Akainu hunts Luffy for being dragons son
How can this be the end boss of Luffy?
Smoker is called wild dog for being a rebel to the marines. Smoker is called white hunter for his persistence
Smoker is the Luffy in the marine organisation, a rebel and persistent “hunter” of his dreams
Akainu is supported by celestial dragons.
Luffys story is about becoming king of pirates,
Luffy’s story is not to avenge Ace