Because he lives in his own world. Fanfiction is something made by fans in our world, not in his magical world. He has no way to know about it.
The reason Harry Potter doesn't care about fanfiction is that he is a character in a specific fictional universe. His world is defined by J.K. Rowling's original story. He is busy with his own quests, like finding Horcruxes and fighting in the Battle of Hogwarts. Fanfiction is a product of fans' creativity outside of his world. He has no connection to it as his focus is on the events and relationships within his own story. There's no mechanism in his world for him to be aware of or care about fan - made stories.
Well, it's hard to say for sure. Since the concept of fanfiction is something that exists outside the main story. Harry Potter within the official story is occupied with his own adventures like fighting Death Eaters and saving the wizarding world. He probably has no idea what fanfiction is, let alone care about it.
Well, Harry Potter has his own real and complex life. He has grown up in a difficult situation, facing challenges and traumas. Fanfiction is a concept from our world, outside of his own experiences. He's more concerned with the things that directly impact him, like the Triwizard Tournament, his relationship with Dumbledore, and the mystery of his parents' death. Fanfiction doesn't have a place in his immediate concerns. He's constantly in a battle against the forces of evil, and that takes up all his attention.
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.
In some fanfictions, Snape's care for Harry is shown through his hidden acts of protection. He might secretly keep an eye on Harry during dangerous situations at Hogwarts, like when there are dark forces lurking around. This could be his way of honoring his love for Lily, Harry's mother.
I think it's not that common. Most fanfictions tend to follow the general traits of the characters from the original books. Since Harry is known for his loyalty and care for his friends, a fanfiction where he doesn't care about anyone is quite the opposite. However, it could be an interesting concept for some authors who want to break the mold and create something new and thought - provoking.
In the context of non - adult Harry Potter fanfiction, 'care less' could potentially refer to a character's attitude. For example, a character might seem to care less about the rules of Hogwarts, like the Weasley twins who often break minor rules with a care - less attitude, adding humor and a sense of rebellion to the story.
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 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.
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.
The foster family characters can be developed in many ways. If they are good - hearted, they could show Harry different values. They might be very strict about magic use, which makes Harry respect the rules more. Or if they are bad, they could have their own motives for taking Harry in, like using him for his fame. Their actions and words can gradually reveal their true natures.