Sasuke might develop more patience. Since Itachi is younger in this fanfiction, Sasuke has to be more understanding. He can't be as impulsive as he usually is. For example, he might have to learn to soothe Itachi when he's scared or upset, which helps Sasuke grow into a more empathetic person.
Maybe Itachi gets sick. Then Sasuke has to take care of him, getting medicine and staying by his bedside. He'd worry about Itachi's health and do everything he can to make him better.
Some popular themes include the exploration of their brotherly bond at a younger age. It could be about Sasuke looking up to Itachi in a more innocent time before all the tragedy. Another theme might be their training together, with Sasuke eager to learn from his older brother. Also, the family dynamic within the Uchiha clan when they were younger can be a focus, like how Itachi's actions even then were subtly influenced by the clan's expectations.
One possible plotline could be that Naruto gets seriously injured during a mission. Sasuke and Sakura, with their combined skills, take him in and nurse him back to health. They might have to deal with Naruto's stubbornness when it comes to resting and following medical advice. Sakura could use her medical knowledge, while Sasuke could provide protection and also train Naruto in new techniques once he's recovered a bit, strengthening their bond as friends.
You can try websites like FanFiction.net. There are tons of Naruto - related fanfictions there, and you're likely to find many stories where Sasuke takes care of Sakura. Just use the search function on the site.
One great story could be 'Sasuke's Gentle Protection'. In this fic, Sasuke is always there to shield Sakura from danger, whether it's during a mission or in the village. He shows his care in small ways, like making sure she has her medical supplies when they're out.
There could be moments of frustration for Naruto, especially when Sasuke is fussy or won't do what Naruto wants him to. But Naruto's love for Sasuke would override that. Emotionally, Naruto would be pouring all his love into taking care of Sasuke, trying to give him the family he never had. And Sasuke, even as a baby, might show signs of his future strong - willed self, which could both amuse and challenge Naruto.
Sasuke becomes more gentle. Usually he is cold and aloof, but with baby Sakura, he has to be soft. He shows more patience as he takes care of her needs, like when she cries and he tries to figure out what's wrong.
Taking care of Naruto might make Sakura more empathetic. She has to understand Naruto's pain and needs, which could make her a better ninja overall. As for Sasuke, it could break down some of his walls. He has to be vulnerable in front of Naruto and Sakura, showing that he's not just the aloof and brooding ninja. This experience might also make him more open to the idea of relying on others and being part of a team again.
One possibility is that Naruto would be extremely clumsy at first. He's not exactly the most domestic type. But his determination to take care of Sasuke would shine through. He might struggle with things like changing diapers or getting Sasuke to eat. However, as time passes, he would start to get the hang of it and form a really strong bond with baby Sasuke.