Well, perhaps the voices Naruto hears are actually the suppressed feelings and thoughts of the Nine - Tails within him. It could be that as he grows stronger, the seal that keeps the Nine - Tails in check weakens a bit, and he starts hearing its voice more clearly. This could lead to a story where Naruto has to learn to co - exist with these voices and even draw power from them in a more controlled way.
In this kind of fanfiction, the plot could be that Naruto starts hearing voices due to some dark jutsu used against him. Maybe these voices are from his past enemies, like Orochimaru, whispering in his mind, trying to break his spirit. And Naruto has to struggle to overcome these voices and not let them influence his actions.
It could be the Sage of Six Paths. Since Naruto has the power of the Nine - Tails and is on a path to becoming a great ninja, the Sage might be trying to communicate with him through voices, guiding him to fulfill some greater destiny.
It could be his parents. Minato and Kushina might be trying to communicate with him from the afterlife. They could be sharing family secrets or just giving him words of love and encouragement.
Well, it could be that Naruto starts hearing the voices of past Hokages. Maybe they're guiding him in some secret mission or giving him advice on how to deal with new threats in the village. For example, the First Hokage's voice might tell him about ancient sealing techniques to use against a powerful enemy.
It could be that Horton hears a story that has a lot to do with the color blue. Maybe there is a blue character in the story he hears that has some kind of adventure.
Another theme is growth. Naruto's discovery of Sakura's thoughts can lead to his own personal growth. He might become more understanding or empathetic. In some fanfictions, after hearing Sakura, Naruto starts to see her in a new light and tries to be a better friend or potential partner. He might work on his own flaws, like his impulsiveness, in order to be more worthy of her feelings.
Draco may first be confused. Fanfiction is a rather strange concept to be singing about. However, as he listens more, he could start to understand the passion behind Harry's singing. This might lead to a moment of self - reflection for Draco. He might wonder if he's been too quick to judge Harry all these years. And perhaps, in a strange turn of events, it could even start to break down some of the barriers between them.
Well, it could also create a really deep connection between them. Since she can hear his thoughts, they might be able to communicate in a whole new way. They could team up more effectively in battles or quests. Annabeth could anticipate Percy's moves and decisions even before he makes them, making them a very powerful duo.
One popular 'naruto hears sakura fanfiction' is 'A Moment of Understanding'. In this fic, Naruto overhears Sakura's true feelings about their friendship and it changes their dynamic in an interesting way.
I'm not sure exactly as I haven't read it. But generally, it might involve a story told through dark and moody illustrations. It could be about characters facing some sort of internal or external struggles, perhaps in a spooky or mysterious setting.
Perhaps in this fanfiction, Naruto discovers that he has some unique weapon - like abilities that are different from his normal jutsu. It could lead to a whole new adventure where he has to learn to control this 'weapon' aspect of himself while still being true to his friends and the village.