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.
He becomes more nurturing. Taking care of a baby forces him to be gentle and patient, which are new traits for him. He might also become more responsible as he has a new life to look after.
Hermione would probably be very practical. She would help with things like making sure the baby has proper nutrition. She might research all the magical and non - magical foods suitable for a baby and create a schedule for feeding. Also, she would help with the baby's education from a very early age, teaching it basic magic concepts.
Well, Naruto might be really confused at first. He's from a world of ninjas and suddenly has to take care of a baby wizard. He'd probably use his ninja skills to protect Harry. For example, he could set up traps around the house to keep bad guys away. And he'd surely try to feed Harry some ramen, which might be a bit strange for a baby used to wizard food.
Naruto would use his Sharingan - like observational skills. He's used to being aware of his surroundings in the ninja world. So he'd be on high alert for any danger. If any dark wizards came after Harry, Naruto could use his speed to get Harry out of harm's way quickly.
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.
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.
Harry's past makes him extremely protective. He lost his parents at a young age, so he would do anything to prevent Pontya from experiencing such a loss. He would be more cautious and use his own experiences of facing danger to keep Pontya safe.
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.