In Akatsuki fanfiction, one of the possible female Uchihas could be an original character created by the author. For example, she might be a long - lost relative of the main Uchiha clan members. She could possess unique Sharingan abilities that set her apart from the male Uchihas in the story.
I'm not sure specifically as there could be many different plots in such a fanfiction. It might involve Sakura having various interactions with the Uchiha clan members, perhaps she forms new friendships, or gets involved in some adventures related to the Uchiha's unique abilities and their history.
Imagine a young Uchiha female who is sent to spy on Orochimaru. But instead of gathering information against him, she gets drawn into his world. Orochimaru's charisma and his mysterious aura attract her. They start a secret relationship, hiding it from both the Uchiha clan and Orochimaru's followers. Their love is filled with secrecy, danger, and a sense of forbidden allure.
A love story could involve an Uchiha female from a different time period who accidentally travels back in time and meets a younger Orochimaru. They start to bond over their shared love for unique jutsus. As they train together, their relationship deepens into love. However, she knows the future of Orochimaru and has to decide whether to try to change his path or accept him as he will become.
The main character is Sakura. For the Uchiha side, Sasuke is a no - brainer as a main character in this fanfiction. But it could also include some other Uchiha characters that are not as prominent in the original series. For instance, a young Uchiha who is just starting to discover their Sharingan powers and Sakura becomes a mentor - like figure to them. Or perhaps an older Uchiha who has survived some great tragedy and Sakura helps them come to terms with their past, all while exploring the unique culture and abilities of the Uchiha clan.
A female Uchiha in Akatsuki fanfiction may act as a mediator. Since the Akatsuki members often have conflicting personalities and goals, her diplomatic skills, enhanced by her Uchiha upbringing, could be used to keep the peace within the group. For instance, she might use her Sharingan to read the emotions of the members and defuse tense situations.
In a 'sakura brother killed the uchihas' fanfiction, the plot could start with the Sakura brother having a hidden power or ability that the Uchihas unknowingly pose a threat to. He might see the Uchihas as a danger to his sister or to the village in general. And as a result, he decides to take matters into his own hands and eliminate them. Or it could be that he is misinformed about the Uchihas and thinks they are evil, leading to his actions.
I haven't come across a 'sakura brother killed the uchihas' fanfiction. It could be a really unique and perhaps not very mainstream idea. Fanfiction often has a wide range of themes, but this seems rather unusual. Maybe it's a very specific creation within a small group of fans.
They might have a stronger Sharingan. Since Izuna was a very powerful Uchiha, his genes could give the descendant a more potent version of the Sharingan, perhaps with quicker activation or less chakra consumption.