One common theme is brotherly love. Itachi's love for Sasuke despite the hardships they face is often explored. For example, in many fanfictions, Itachi sacrifices a lot to protect Sasuke.
One popular 'little Sasuke and Itachi fanfiction' is 'The Bond Beyond Blood'. It beautifully portrays the relationship between the two brothers at a young age. It shows Itachi's protective nature towards Sasuke and Sasuke's admiration for his older brother.
Sure. Itachi's saving of Sasuke was a crucial moment in the manga. It was tied to his hidden motives and sacrifices for the greater good of the ninja world and Sasuke's future.
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.
A possible fanfic could focus on a parallel universe where Itachi and Sasuke are not bound by the same clan conflicts. In this universe, they could meet in a more peaceful setting, like a small village. Their relationship could develop gradually as they discover shared interests. For example, they might both be interested in learning about ancient ninja arts, and through this common ground, a yaoi - inspired relationship could start to form.
One common theme is the struggle against family and clan expectations. In the Naruto universe, the Uchiha clan has a strict code. Sasuke being in love with Itachi goes against the normal family dynamic. Another theme is self - discovery. Sasuke has to come to terms with his feelings which are not only unorthodox but also might make him question his identity.
In fanfiction, Sasuke and Itachi's brotherly love is often depicted in very complex ways. Some stories focus on Sasuke's journey to understand Itachi after his death. He discovers the truth behind Itachi's actions, which were all to protect him and the village. This realization deepens his love and respect for his brother.
Fanfiction.net is also a good place to search. However, the tagging system might not be as detailed as AO3. But if you dig a bit and look through the Naruto section, especially in the Itachi and Sasuke character - centric stories, you may come across such a fanfiction. Some writers might be more subtle about it and not have the kiss as an obvious part of the title, so you'll need to read the summaries too.
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.
The main themes usually include sacrifice. Itachi sacrificed a lot for the village and for Sasuke. Fanfictions may expand on this, showing how Sasuke comes to terms with it. Another theme is the search for truth. Sasuke was on a quest for the truth about Itachi, and this journey is often explored in non - lemon fanfictions. And of course, the theme of growth. Both characters grow and change throughout their relationship, which is a key aspect in many of these fanfictions.