Maybe Harry discovers a baby snake in the Forbidden Forest and decides to take it under his wing. He could use his Parseltongue ability to communicate with it and keep it hidden from the other students and teachers.
Well, perhaps there's a situation where Voldemort's snake Nagini has an offspring. Harry, out of a sense of trying to prevent more dark magic from being spread, takes in the baby snake. He tries to raise it in a way that it doesn't inherit the evil nature of its parent. He might teach it about kindness and the value of life using his Parseltongue. This would be a very unique take on the Harry Potter world as it involves him trying to reform a creature that is often associated with the dark side.
Maybe it's a dark wizard who has an interest in the snakes Harry is taking care of. He wants to use the snakes for some dark magic purposes. So he constantly tries to steal the snakes from Harry or even harm Harry to get to the snakes. For example, he could be a follower of Voldemort who believes the snakes hold some special power that can help bring back the dark lord.
Well, maybe Harry discovers an injured snake in the Forbidden Forest. He decides to take it back to the Gryffindor common room and hides it in his trunk. He uses his magic to heal the snake and then starts to feed it small magical creatures. Eventually, the snake becomes his secret pet and helps him out in some tricky situations, like warning him of approaching danger.
One possible plot could be that after the death of Dumbledore and with the Order of the Phoenix in disarray, Harry decides to go into hiding alone. He uses his skills in magic, like the Patronus charm for protection and the Invisibility Cloak to avoid detection. He might start to forage for his own food in the Forbidden Forest, using magic to find edible plants and hunt small magical creatures in a humane way. He also spends his time studying advanced magic on his own to become stronger, preparing for the final battle against Voldemort.
One possible plot could be that Harry, using his magic skills, protects Naruto from the various threats in the Naruto universe. For example, he could use spells to shield Naruto from enemy ninjas' attacks. He might also use his knowledge of magic to help Naruto understand some concepts that are difficult in the ninja world, like a different way of looking at chakra manipulation which could be related to how magic works in Harry's world.
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.
One possibility could be that the snakes are magically bound to protect Harry. Maybe they are under an ancient spell that makes them his guardians. For example, they could form a protective barrier around him whenever he is in danger, like when Voldemort or his Death Eaters are near.
Well, perhaps in this fanfiction, Harry discovers he has an affinity for snakes early on. Maybe he's able to communicate with them in a deeper way than Parseltongue allows. The snakes could train him in stealth and survival skills, like how to move quietly in the Forbidden Forest or find hidden passages. They could also teach him some unique magic that is related to the ancient magic of serpents.
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.
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.