Itachi's personality could become more outwardly friendly. In the ninja world, he had to keep many secrets and be aloof. But in the wizarding world as Harry Potter, he might find it easier to let people in. He may also be more assertive in a different way. Instead of silently following orders like in his past life, he could take the lead in situations, using his own judgment based on his past experiences and newfound magical knowledge.
Sasuke would likely become more protective. Usually Sasuke is very focused on revenge and his own power, but when faced with baby Itachi, he would feel the need to shield him from all harm. His cold exterior might soften a bit as he looks at the innocence of baby Itachi.
His personality would likely be more introverted. Itachi was a rather quiet and introspective person, and this trait would rub off on Harry. Harry would probably be more cautious in his actions and less impulsive.
Naruto's normally upbeat and energetic personality might become more subdued. He'd have to face the reality of his own mortality, which could make him more cautious and less impulsive.
In Itachi yaoi fanfiction, Itachi is often depicted as a complex and mysterious character. He is usually highly intelligent and powerful, which makes him an alluring figure in romantic or relationship - based stories. His loyalty, whether it be to his family, his village, or his love interest in the yaoi context, is also a common characteristic explored.
Fem Harry would likely be more reserved in her emotions. Itachi is a rather stoic character, and growing up with him would influence Fem Harry to keep her feelings more to herself. In contrast to the original Harry who often wore his heart on his sleeve.
He would likely be adapted as a very powerful and mysterious character. His skills in the Naruto universe would translate into some sort of special magical abilities in the Harry Potter world. For example, his Sharingan could be like a super - powerful magical eye that gives him unique insights.
Sasuke is often paired with Itachi in these fanfictions. Since they are brothers, when Itachi time - travels, his interactions with Sasuke are crucial. Sasuke might be at a different stage in his life, and Itachi could try to influence his development. Another common character is Naruto. Naruto's ideals of friendship and peace could contrast with Itachi's more complex and tragic view. Their interactions could lead to interesting plot developments.
Sasuke is often paired with Itachi in these fanfictions. Their complex relationship from the original Naruto series can be explored in new ways in another world. For example, they might be on a mission together in a world full of unknown dangers. Another popular character to be paired with Itachi is Naruto. Their different outlooks on life and friendship can create interesting dynamics, especially when they are in a strange new world where they have to rely on each other more than ever. Shisui could also be paired with Itachi. Since they were friends in the original story, in the fanfiction, they could be reunited in another world and face challenges together, perhaps against a new and powerful enemy.
Well, there might be characters from their clan. Since Itachi is from the Uchiha clan, other Uchiha members could play significant roles. They could be elders or other young Uchiha who are involved in the clan's affairs and in turn, affect Itachi and Izumi's story.