Well, clearly Harry is one of the main characters as he is the one taking care of the baby cousin. The baby cousin is also a main character, even if it's a young and not fully developed character yet.
It's possible that some of Harry's family members could also be involved. Maybe his aunt or uncle, who are related to the baby cousin. They could either be supportive or create some sort of conflict in the story. Their presence would add more depth to the situation of Harry taking care of the baby cousin.
There could also be other characters in the background. For example, Harry's friends might pop in to check on how he's doing with taking care of the baby. So Ron and Hermione could be secondary characters that play a part in the story. They might offer advice or just be there to witness the cute interactions between Harry and the baby cousin.
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.
Maybe it's the child of one of his friends or allies. For example, it could be the baby of Ron and Hermione. Harry would then be taking care of the baby out of loyalty and friendship.
Harry might first try to figure out what's wrong. If the baby is hungry, he'll quickly get a bottle. If it's a wet diaper, he'll change it. Sometimes, he just holds the baby close and rocks it gently, humming a little tune. He doesn't get frustrated easily because he really cares about the baby.
Well, Harry might use his magic to make the baby laugh. For example, he could turn the baby's rattle into a little magical creature that dances around. He'd probably also be very protective, like how he was with his friends at Hogwarts.
A heartwarming moment could be when Harry takes the baby out for a walk. He pushes the stroller carefully, talking to the baby about all the things they see around them, like the colorful flowers and the friendly squirrels. And at night, when the baby has a nightmare and Harry stays up all night comforting it. He rocks the baby gently and whispers soothing words until the baby calms down and falls back asleep.
One possible plot could be that Harry discovers a time - traveling accident has brought baby Snape to his present. Harry, being the kind - hearted person he is, takes it upon himself to care for the baby. He has to figure out how to feed the baby, keep him clean and comfortable. Maybe he also has to protect baby Snape from any threats in the wizarding world that might target Snape even as a baby.
One possibility could be that Draco is forced into taking care of Harry due to some magical circumstances. Maybe there's a spell gone wrong that makes it his responsibility. He initially resents it but as he spends time with baby Harry, he starts to see the innocence in him and develops a soft spot.
In this fanfiction, perhaps Harry could struggle at first with the basic tasks like feeding and changing the baby. He might make mistakes but learn quickly.
Harry is known for his kindness and loyalty. So, he would take care of Draco with a lot of patience. He would probably stay up all night if Draco was fussy, just to make sure he was okay. His protective nature would also mean he'd keep Draco safe from any harm, whether it's from other wizards or just from the general dangers in the wizarding world.
The story could center around the magical ways Harry uses to take care of baby Hermione. Since they are in the wizarding world, he could use spells to make feeding time easier or to keep her entertained. He might also have to protect her from any dark forces that might be lurking around. And along the way, he discovers a new side of himself, the side that is very nurturing and loving.