The 'akaza sad story' might refer to the tragic backstory of Akaza from Demon Slayer. Akaza was once a human with a strong will. He had a family and a normal life, but due to various misfortunes and being turned into a demon against his will, he lost his humanity and was forced to do cruel things. He also had a lot of inner struggles as he still retained some of his human emotions deep down, which made his story a sad one.
Well, Akaza, originally Hakuji. He was a kind - hearted young man at first. He got involved with some bad people who took advantage of his situation. His love for the girl was pure, but they couldn't be together. When he became a demon, he lost some of his human memories but not all. His back story is full of pain and loss, which in a way, shapes his character as a demon. He is a complex character with a past that has both human and demonic elements intertwined.
One key element is his human life as Hakuji. His poverty and his attempts to care for his father are important. Another is his love for the girl, which was a major part of his human existence. And of course, his transformation into a demon due to the misdeeds of others towards him.
One common theme is the clash of ideologies. Akainu has a very strict and uncompromising view of justice in his original story, while Naruto has a more forgiving and rehabilitative view. So when they interact in fanfiction, this clash often forms a central theme.
One good Admiral Akainu fanfiction could be 'Akainu's Redemption'. It might explore his character in a new light, showing his journey towards a different perspective. Another could be 'Akainu in the New World' which could detail his adventures in uncharted territories. There's also the possibility of 'Akainu's Hidden Past' that delves into his backstory and what made him the person he is in the original story.
Well, it could be about Naruto having to deal with the strict and fiery nature of Akainu as his father. Maybe Naruto has to adapt to a more military - style upbringing while still holding onto his own ninja values.
I'm not entirely sure what about this 'One Piece' fanfic has made you furious. Maybe the author took some liberties with Akainu's character that you didn't like? For example, if they made him act out of character in a way that didn't seem true to the original 'One Piece' story.
It could be that the fanfic misrepresented Akainu's power levels. In 'One Piece', Akainu is a very powerful character, and if the fanfic made him seem weak or overpowered in an unrealistic way, that would be annoying.
I'm not sure specifically what that 'akainu this bites one piece fanfic' is about without reading it. It could potentially be a fan - created story in the One Piece universe that focuses on Akainu and some sort of 'biting' action, which might be a metaphorical or literal element in the story.