The biggest difference is the creativity of the fanfiction writers. In the anime, the fight follows a set storyline. But in fanfiction, anything can happen. For example, Naruto could suddenly gain a new power that was never in the anime. It's like a whole new world of possibilities.
A theme that often comes up is his physical pain and how he endures it. This can be used to show his strength and tenacity. For example, in a battle - themed fanfiction, he endures great pain but still manages to fight for the sake of his village. Also, the theme of self - discovery through pain is common. As he experiences pain, he learns more about himself and his limits.
The 'jiraiya vs pain' in RWBY fanfiction could be a battle of wits as much as a battle of powers. Jiraiya is a very experienced ninja, and Pain has his own ideology - driven powers. In a RWBY setting, the battle could be affected by things like Dust, the special energy source in RWBY. Jiraiya might be confused by this new element at first, while Pain could try to incorporate it into his attacks. It would be a clash of two different power systems and fighting styles.
McGregor's unruly behavior and his disrespect towards Khabib. He said things that were completely unacceptable. Khabib, being a proud fighter with strong values, couldn't let those remarks slide. So, he took on McGregor in the fight to set things straight and prove his worth in the MMA world.
Minato might also be a prominent character. As their teacher, he can influence the way Obito and Kakashi interact. In some fan fictions, he could be the one to help them resolve their differences or provide some crucial information about their past that changes their current situation.
The theme of sacrifice could also be present. Both characters are willing to sacrifice for their causes. In the context of a yaoi fanfiction, this could translate into sacrifices for each other. For example, Pain might sacrifice his original plans for world domination for Kakashi, or Kakashi might put his village - related duties on hold to be with Pain, exploring the lengths they would go for their relationship.
Another possible fanfiction could be centered around Kakashi's pain from his past traumas, like the loss of his father. It could show how these past experiences resurface when he faces a new threat in the village. The story could detail how he overcomes this pain by finally coming to terms with his past and using it as a source of strength.
Some fanfictions might explore the emotional aspect of their fight. For example, how their past friendship affects the battle. Maybe Kakashi hesitates to strike a fatal blow because of their shared history.
There was a girl and a boy in a competition. It was a race. The boy was overconfident and made some taunting remarks towards the girl before the race. This made the girl determined to win. During the race, the boy tried to block the girl's path a few times. The girl, not one to be bullied, elbowed him gently but firmly out of the way. In the end, the girl won and the boy was left fuming. But the girl just walked away with a proud smile on her face.
Once, I saw a wife and a mistress have an argument in a park. The wife found out about the mistress and confronted her. The mistress tried to act tough at first, but the wife was full of anger and rightful indignation. The wife started shouting about how the mistress was ruining her family. In the end, the mistress, feeling ashamed, ran away.