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.
There could be a situation where they are in danger. Sasuke has to protect Itachi. He'd use his skills to fend off enemies and make sure Itachi is safe. At the same time, he'd also be teaching Itachi how to be more aware of his surroundings and protect himself in the future.
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.
One common scenario is when Naruto gets injured during a mission. Sasuke, being the one to take care of him, uses his skills to heal Naruto or at least keep him stable until proper medical help arrives. Another scenario could be Sasuke protecting Sakura from an enemy's attack, perhaps even sacrificing himself a bit in the process. And sometimes, Sasuke might help Sakura in her medical research, providing her with rare herbs or knowledge he's acquired during his travels.
In such fanfiction, McCoy might struggle with understanding Spock's unique Vulcan needs as a baby. For example, he could be puzzled by Spock's early telepathic abilities or his different dietary requirements compared to human babies.
One possible scenario is that Anko takes Naruto on special training missions in dangerous and unexplored areas. This would not only strengthen Naruto's skills but also build their bond. Another could be Anko helping Naruto deal with the pressure of being the Jinchuriki, perhaps by sharing her own experiences of dealing with difficult things in the ninja world.
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 common scenario is Snape protecting Draco from the other Death Eaters. Since Draco is young and somewhat naive in the ways of the Dark Arts and the Death Eater world, Snape steps in to keep him safe. Another scenario could be Snape helping Draco with his schoolwork, especially in Potions. Snape, being a master of Potions, would be able to guide Draco and boost his confidence in that subject.
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.
One interesting scenario could be Poseidon using his powers to create a mini - underwater world for baby Percy to explore safely. He might make colorful fish swim around Percy and gentle sea currents act like a cradle.
Maybe Harry tries to feed the baby cousin some magical baby food. He could make funny faces to get the baby to open their mouth and eat. It would be really adorable to see the baby's reaction to the new flavors.
Well, perhaps when Sasuke protects baby Sakura from a small danger, like a wild animal approaching. He stands in front of her, kunai in hand, his eyes full of a fierce protectiveness. And also when he tucks her in at night, making sure she's warm and comfortable, it's really sweet.