One interesting 'akuma naruto fanfiction' could be about Naruto facing an akuma - like demon that has unique powers. Maybe the demon has the ability to manipulate time, and Naruto has to find a way to overcome this new and powerful foe using his own skills and the help of his friends. Another story might involve Naruto being possessed by an akuma and his friends having to find a way to save him without harming him.
Sasuke. If Sasuke had an Akuma no Mi power, like the Goro Goro no Mi (Rumble - Rumble Fruit), it would make him even more formidable. He could use lightning - based attacks from his ninjutsu in combination with the electrical powers of the fruit. His already brooding and powerful character would become even more complex and dangerous.
I'm not sure if there is a specific fanfic exactly like that. There are so many Naruto fanfics out there, and while some might involve Naruto having an interest in Akuma in some creative crossovers, it would take some serious searching through fanfic platforms to find one.
First, you need to have a clear idea of what an akuma is in the context of Naruto. Is it a new type of demon? A dark spirit? Once you've defined that, think about how it will interact with Naruto and the other characters. You can start with a simple premise like Naruto encountering the akuma on a mission. Then, just start writing and let the story unfold as you go.
One interesting concept could be how the powers of the Akuma no Mi would interact with the ninja abilities in Naruto. For example, if a character had a Logia - type Akuma no Mi, like the Mera Mera no Mi (Flame - Flame Fruit), they could use it in combination with fire - based ninjutsu to create more powerful attacks. Another concept might be the clash of values between the One Piece world where the Akuma no Mi exist and the Naruto world. In the Naruto world, they value things like teamwork and honor in a different way compared to the pirates in One Piece.
In some 'Naruto Akuma' fanfictions, Akuma could be a mentor figure to Naruto. Since Akuma has his own set of unique and powerful abilities, he could teach Naruto different combat techniques or ways to tap into new sources of power. This would change the dynamic of Naruto's growth and his relationships with other characters in the series.
Another place is FanFiction.net. There are some really good and unique 'Akuma no Riddle' fanfics there. Just use the search bar and type in 'Akuma no Riddle' to find relevant stories.
One great 'Akuma no Riddle Fanfiction' is 'The Unspoken Bond'. It delves deep into the complex relationships between the characters. The author does an amazing job of exploring the emotional depth that the original series only hinted at.
Harry Potter himself is a likely candidate. Given his heroic nature and the need to constantly fight against dark forces, an Akuma no Mi could be a great addition to his arsenal of skills. It would give him new ways to protect his friends and defeat his enemies.
Title: 'The Akuma of the Mysterious OC'. In this fanfiction, my OC, Lila, is a shy artist in Paris. One day, she gets akumatized because her art was rejected for an important exhibition. Hawkmoth takes advantage of her sadness and anger. As the Akuma, she gains the power to turn all art in Paris into chaos. Ladybug and Chat Noir must find a way to save her and Paris.