Well, one reason could be Sasuke's continued obsession with his revenge. He might be so focused on it that he ignores Sakura's feelings and concerns, which could lead to a fight. For example, if Sakura tries to persuade him to let go of his revenge and he refuses, it could spark an argument.
It could end with a draw. They both realize that they are equally matched and that their fight is not really getting them anywhere. They might then decide to have a more civilized conversation to resolve their differences.
It really depends on the writer's perspective. Some might have Naruto win because of his unwavering belief in friendship and his ability to draw strength from those around him. His large pool of chakra and his various powerful jutsu could give him the upper hand.
It could make their relationship stronger in the long run. After the fight, they might realize how much they actually care about each other. They could start to communicate better and understand each other's perspectives more deeply.
The most epic moment could be when Sakura finally lands a hit on Sasuke after a long and intense battle. After dodging his Sharingan - enhanced attacks for so long, she uses her chakra - enhanced strength to break through his defenses and send him flying. It would be a moment of triumph for her, showing how far she has come in her strength and skills.
For Naruto, he might become more determined to bring Sasuke back to the right path. The fight in the bathroom could be a turning point where he realizes that he can't just use words but also has to show his strength. Sasuke, on the other hand, could start to question his own motives a bit more. Maybe seeing Naruto's unwavering spirit in such a strange setting makes him think twice about his actions.
One interesting scenario could be that Naruto and Sasuke discover a new power within themselves during the fight that changes the whole dynamic. Maybe Naruto unlocks a new form of Sage Mode that gives him an edge, and Sasuke responds with a new sharingan evolution.
Naruto often has his Nine - Tails chakra at his disposal. This gives him a huge boost in strength, speed, and endurance. He can also use his Rasengan, which is a highly concentrated ball of chakra. Sasuke, on the other hand, has his Sharingan, which allows him to predict his opponent's moves and copy some jutsus. He also has his Chidori, a powerful lightning - based attack. So Naruto's power is more about raw strength and stamina from the Nine - Tails, while Sasuke's is more about precision and speed with his Sharingan and Chidori.
In a great Naruto Sasuke fight fanfic, the moment right before they reach their physical limits can be extremely intense. Their bodies are bruised and battered, but their eyes still burn with a fierce determination. They've been at it for what seems like hours, and the battle has taken them through various terrains, destroying everything in their path. At this point, they both know that the next move could be the decisive one. Naruto, with his unwavering belief in friendship, and Sasuke, with his thirst for power and revenge, are at a standstill, but the tension in the air is palpable, like a storm about to break.
Maybe it's about protecting Sakura. Itachi might think that Sasuke isn't the right person for Sakura and wants to protect her from Sasuke's darker side. And Sasuke, on the other hand, believes he can protect Sakura better than Itachi and that Itachi has no right to interfere.