Most likely Naruto and Sasuke. In the original series, they were already very powerful when they faced Kaguya, and in fanfiction, they could be even more so. Their combined strength and determination usually make them the favorites to win.
He might feel anger. Since he was so set on revenge against Itachi, any portrayal that didn't match his view of himself as the victor could make him angry.
In a small town, there lived a good guy, Lily. She was a teacher. A bad guy, Mr. Dark, who was a drug dealer, was trying to corrupt the local youth. Lily noticed his activities. She gathered evidence secretly. Then, she bravely confronted Mr. Dark in front of the whole town. The townspeople supported her. They helped to arrest Mr. Dark, and Lily continued to educate the children to stay away from bad things.
I think young Sasuke would have a very intense reaction. He was so consumed by his hatred for Itachi at that young age. A Sasuke vs Itachi fanfiction would be like a trigger for him. He would be eager to see how the fictional fight is portrayed. If Sasuke in the fanfiction is shown as strong, it might fuel his own ego and make him strive even harder to become powerful. However, if the fanfiction shows Itachi as superior, it could enrage him. He might feel that it undermines his own goal of defeating Itachi and he might even want to find the writer to correct their 'wrong' view.
He might meet the future versions of Naruto and Sakura. Their relationship with him could be very different in the future, perhaps they are now leaders of the village and Sasuke has to adjust to their new status.
I like Naruto in these fanfics because he always stays true to his beliefs. He is constantly trying to bring Sasuke back to the village and is willing to fight for their friendship.
One of the best moments is when they have a rematch that showcases their growth. Naruto has become stronger with his new jutsu, and Sasuke has further mastered his Sharingan powers. The intense battle of ideologies during the fight is captivating.
The guy could be thinking about how confident she seems. If she's walking tall and has a certain air about her, he may be in awe and thinking about how he wishes he could be more like that. For instance, if she's in a business suit and looks very self - assured, he might be thinking about how she must be successful in her career. He might also be thinking about how he could start a conversation with her without seeming creepy.
One common theme is justice. The good guy is usually fighting for what is right and fair, like in a story where a detective (the good guy) chases a criminal (the bad guy) to make sure the law is upheld. Another theme is sacrifice. Sometimes the good guy has to give up something to defeat the bad guy, for example, a hero leaving his family to go on a dangerous journey to stop an evil force. Also, redemption can be a theme. Maybe the bad guy has a chance to change in the story, but often they don't take it and the good guy has to force the situation to a conclusion.
They could be colleagues. The 50 - year - old guy might have more seniority at work, while the 35 - year - old is still climbing the corporate ladder. They might work together on projects, with the older one providing guidance based on his years of experience.