The themes of secrecy and acceptance are also common. Sasuke would likely have to keep his love for Itachi a secret due to the social norms in the ninja world. And acceptance comes in when he has to accept his own feelings and perhaps hope that others, if they were to find out, would also accept it. There's also the theme of sacrifice, as Sasuke might be willing to sacrifice a lot for his love for Itachi, whether it's his standing in the village or his relationships with others.
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.
One common theme is forgiveness. Sasuke has to forgive Itachi for all the pain he caused him, like killing their clan. In fanfiction, this process of forgiveness can be very detailed and emotional.
A common theme is protection. Itachi is often depicted as protecting baby Sasuke from various threats. Another theme is brotherly love. It shows their bond even when Sasuke is just a baby. Growth is also a theme, as we can see how Sasuke might grow up under Itachi's influence in the fanfiction.
One common theme is redemption. Sasuke often sees Itachi in a new light and this helps him find a path towards redemption. He realizes that Itachi was not the monster he once thought and his love for Itachi becomes a part of his journey to make amends for his past actions.
One common theme is revenge. Sasuke's thirst for revenge against Itachi is often explored in great detail. Also, friendship, especially Naruto's friendship with Sasuke, is a big theme. Naruto's attempts to bring Sasuke back from the path of vengeance. Another theme is sacrifice, as Itachi's self - sacrificing actions for the greater good are often a central part of the stories.
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 common theme is redemption. For example, Sasuke often has a journey of redeeming himself after his dark turn. Another theme is friendship, like how Naruto's unwavering friendship for Sasuke is a central part. Also, the idea of sacrifice, as seen with Itachi's great sacrifice for the village and his brother.
One common theme is redemption. For example, Itachi's actions are often explored in a way that he tries to atone for his past deeds. Naruto usually helps in this process as he believes in the good in people.
One common theme could be the exploration of Sasuke's emotional turmoil. Since Itachi is abusing him in this fanfiction, Sasuke might be shown as confused, angry, and deeply hurt. Another theme could be the power dynamic between them. Itachi being the abuser might have a significant amount of power over Sasuke, which could lead to themes of helplessness on Sasuke's part. Also, themes of revenge might be present. Sasuke might be constantly thinking about getting back at Itachi for the abuse, which could drive the plot forward in the fanfiction.
One common theme is the struggle between love and power. Since Itachi is a vampire, he often has to balance his newfound power with his love for Sasuke. Another theme is the idea of forbidden love, as their relationship might be seen as taboo in the context of vampire and human (or in this case, another Uchiha).
Reconciliation is a big theme. Itachi and Sasuke's relationship is often at the center of this. Naruto can be the catalyst in these stories, helping them to reconcile their differences. There are also themes of sacrifice, as Itachi has already sacrificed a lot in the original story, and fanfictions may expand on this concept in relation to all three characters.