In some fanfictions, her plot could revolve around time - travel. She might accidentally travel back in time and meet her father when he was a student. This would give her a chance to see a different side of him and understand his choices better. She could also try to change some events in the past to make a better future. However, this would bring a lot of consequences and she would have to deal with the butterfly effect in the wizarding world.
One interesting plot could be Snape raising Harry while secretly training him in advanced potions and dark arts defenses. Harry would grow up with a different perspective on Snape, seeing him as a strict but caring father figure. Another plot might involve Snape having to protect Harry from other dark wizards who suspect Harry's true potential. This could lead to some intense magical battles and Snape using his knowledge and skills to keep Harry safe.
A really unique plot could be Snape adopting Harry during a time when Voldemort is still a threat. Snape has to balance protecting Harry from Voldemort's followers and also from the prejudice within the wizarding community. He might train Harry in Occlumency more intensively, and in the process, they develop a deeper understanding of each other. Harry starts to see Snape not as the mean professor but as a complex person with his own traumas and reasons for his actions.
One interesting plot could be that Snape secretly follows Harry during a dangerous wizarding tournament task and intervenes when a dark creature is about to attack Harry without revealing his identity. This would add a layer of mystery and show Snape's hidden care for Harry.
Perhaps she has a special magical ability that is different from her father's. This ability could draw the attention of both good and bad forces. She has to learn to control it while also dealing with the expectations placed on her because of her father. For example, if she has the ability to communicate with magical creatures in a way no one else can, she might be pressured to use it for the benefit of the school or be targeted by those who want to use it for evil.
Perhaps in a story where there's a spell gone wrong. The spell causes Snape and Hermione to be linked in a strange way. They start to experience each other's emotions and memories. As they work together to break the spell, they develop a deep connection and Snape, who has always been a complex character, shows a softer side and kisses Hermione as a sign of his new - found feelings.
Some plots might involve Snape being forced to confront his new - found relation to Voldemort in the middle of the wizarding war. For example, he could be captured by Voldemort's forces and Voldemort reveals the truth to him. Then Snape has to decide whether to embrace this new identity or fight against it. There could also be a plot where other characters like Harry and Hermione suspect Snape's relation to Voldemort and try to prove it.
One common theme is identity. Since she is Snape's daughter, she often struggles with defining herself apart from her father's complex legacy. Another theme is acceptance, both from the Hogwarts community and within her own family. For example, in many fanfics, she has to prove herself worthy to be in Slytherin like her father.
One possible plot could be that Snape has been poisoned and his body is reacting violently, leading to him throwing up. This could be part of a larger mystery where someone is trying to harm him within the Hogwarts walls. Another idea is that he's having a severe emotional reaction to a memory that resurfaces, perhaps related to his past with Lily or his difficult childhood. It could also be that he's under a dark spell that has unexpected side effects on his physical state.
One interesting concept is a fanfiction where Severus Snape time - travels. He could go back in time to change certain events, like trying to save Lily earlier or prevent Voldemort from rising in the first place. This would create a whole new set of plotlines and character interactions.
One great Severus Snape daughter fanfiction is 'The Snape Legacy'. In this story, his daughter has to navigate the complex world of Hogwarts while carrying the weight of her father's reputation. It shows her growth from a shy girl to a powerful witch, with interesting plot twists involving her relationships with other students and teachers.