Harry would likely be a loving and doting father. He'd teach her everything he knows about magic, from basic spells to advanced defensive magic. However, he might also be a bit overprotective because of his own past traumas. He would have a close relationship with her, sharing stories of his adventures at Hogwarts and during the fight against Voldemort.
Percy would use his combat skills. He has a lot of experience in fighting monsters, so if any threats come near his daughter, he'd be ready to fight them off with his sword. He'd also use his strategic thinking to outwit enemies.
One possible plot could be that Harry's daughter discovers she has magical powers just like her father. She might struggle at first to control them and face some challenges at Hogwarts, but with the help of her father's wisdom and her own determination, she overcomes difficulties and becomes a great witch.
This type of novel was generally called "The Story of the Vermilion Fruit in the City of Farming." The protagonist was usually a person with an ordinary life, but by chance, he got a magical plant, the Vermilion Fruit, and used it to start his farming journey in the city.
The protagonist gradually discovered the magical effect of the red fruit in the process of farming and began to use it to improve his life. For example, he could earn wealth by planting the Vermilion Fruit, and he could also use it to help others in need.
In novels, the protagonist's daughter was usually an important character. She had an affinity for animals, which allowed her to make better use of the red fruit to help humans and animals. The protagonist may also encounter some challenges and difficulties, such as the problems he has to face in order to maintain his farming career and family relationships.
This was a story full of warmth and fantasy. The protagonist was constantly looking for peace and happiness in his heart while farming in the city.
Dumbledore might also show up in these fanfictions. He could be a guiding spirit, appearing in Harry's dreams or visions to give him advice on how to raise his daughter in the wizarding world. Neville could be another character that pops up, perhaps as a teacher at Hogwarts who has a special connection with Harry's daughter.
Fanfiction that involves sexual content between characters is often not appropriate. Harry Potter is a widely loved series aimed at a broad audience, including young readers. Such fanfiction goes against the family - friendly and magical essence of the original work.
In many fanfictions, Neville Longbottom's son or daughter is paired with Harry's daughter. Given Neville's importance in the wizarding world, their children's relationship can be really engaging. They could be partners in a herbology project, and through that, develop a deeper connection. Also, the children of Luna Lovegood are sometimes paired with Harry's daughter. They might share an interest in the more esoteric aspects of magic and go on adventures to discover new magical creatures or phenomena together.
Snape is a complex and often brooding character. His daughter might initially find it difficult to get close to him. He would probably be strict in teaching her magic, especially potions. But his underlying love and protectiveness would show in small ways, like making sure she has all the ingredients she needs for her potions work. His reserved nature might make her feel like he doesn't care much, but as she grows older, she would understand that his actions speak louder than his words.