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.
It could be really interesting. Maybe Naruto would be fascinated by Akuma's power and try to learn from it in some way. He might see Akuma as a new form of strength that he could incorporate into his own ninja skills.
One plot idea could be Naruto being transported into the Street Fighter universe and having to team up with Akuma to face a new, powerful threat that endangers both their worlds. Maybe a dark force is trying to merge their dimensions and they must use their unique skills to stop it.
Naruto's fighting style focuses on ninjutsu like the Rasengan and Shadow Clone Jutsu. Akuma has his powerful Hadoken and Shun Goku Satsu. In this fanfic, Naruto could use his clones to distract opponents while Akuma charges up a powerful Hadoken. Or Naruto could incorporate Akuma's fast - paced martial arts moves into his own taijutsu.
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.
Since I haven't read this particular 'akuma no riddle banba fanfic', it's hard to say for certain. However, generally in fanfics for 'Akuma no Riddle', they often explore the relationships between the characters in more depth. Maybe this one with 'Banba' focuses on his backstory, or his relationships with other characters in a way that the original work didn't fully explore.
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.
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.
One interesting Akuma OC fanfic could be about an Akuma OC with unique powers that are different from the typical ones. For example, an Akuma OC who can control time in a very limited and strange way, like only being able to freeze time for a few seconds at a time, but those few seconds are crucial in battles or important events. Another could be an Akuma OC that has a complex backstory involving a family curse that led to their transformation into an Akuma. They struggle with their new identity while trying to find a way to break the curse.
The fanfic might focus on the unique dynamics between Tokaku and Haru. For example, it could show how their personalities, one being more reserved perhaps (Tokaku) and the other more open (Haru), complement each other. It may also explore their shared experiences and how those shape their relationship within the story.