Perhaps in the fanfiction, Snape and Harry are forced to team up to defend Hogwarts against a new, unknown dark force. They have to rely on each other's skills and knowledge, with Snape using his potions expertise and Harry his courage and Gryffindor - like bravado. Along the way, Snape shares some of his own experiences with dark magic and how to combat it, making Harry a more well - rounded wizard.
One interesting plot idea could be that Snape, in raising Harry, teaches him advanced potions from a very young age. Harry becomes a prodigy in potions, much to the surprise of the other Hogwarts students. Another idea is that Snape's strict but fair upbringing makes Harry more reserved and less impulsive, which changes the way he interacts with his friends. He might be more cautious and calculating in his actions, especially when dealing with enemies like Voldemort.
One plot idea could be that Dudley somehow gets involved in the wizarding world due to a magical accident. Snape, initially reluctant, has to keep an eye on him. Meanwhile, Harry is caught in the middle, trying to balance his relationship with Dudley and dealing with Snape's grumpiness. For example, Dudley could accidentally drink a potion meant for someone else and start showing magical abilities, leading to chaos and an unlikely alliance between him and Snape to reverse the effects.
One idea could be that during the duel, Harry discovers a hidden spell that Snape was about to use against Voldemort. So instead of a full - on fight, they end up in a truce to discuss this new revelation. This could lead to a whole new understanding between them.
A plot could be that Snape's pet is a phoenix, which is a very rare and powerful magical creature. Harry Potter is intrigued by this phoenix and tries to get closer to it. Snape is initially against this but as the story progresses, he sees that Harry has a pure heart and allows him to interact with the phoenix. This could lead to a bond forming between Harry and Snape through their shared interest in the phoenix.
Snape's complex character makes him an interesting mentor. His past, especially his relationship with Lily, adds depth. He has a vast knowledge of magic, especially the Dark Arts and potions. For example, in many fanfictions, he can teach Harry unique spells and ways to defend against the Dark Arts that others can't.
One idea could be that Snape discovers a new dark magic plot against Harry early on. He then uses his position as a double agent to mislead the dark wizards while secretly training Harry in advanced defensive magic. For example, he takes Harry to a hidden chamber in Hogwarts at night to practice spells that are not taught in regular classes.
One idea could be that Harry discovers the truth about his parentage early on. This changes his relationship with Dumbledore as he realizes Dumbledore had been keeping this big secret from him. He might also struggle with his identity, feeling torn between the Gryffindor ideals he was raised with and the Slytherin traits he might inherit from Snape.
A plot could be where a rare and endangered creature chooses Harry and Snape as its protectors. They must travel to different magical locations to find a safe haven for it. This would force them to interact and rely on each other's skills.
One plot idea could be Snape teaching Harry some long - forgotten dark arts defenses that were once known only to the founders. This could put Harry in a unique position in his battles against Voldemort. Another idea is that Snape reveals to Harry some secrets about his mother, Lily, that help Harry understand his family better and give him more motivation in his fight. Also, Snape could mentor Harry in potions in a more personal way, sharing his own experiences and insights which could lead to Harry creating new and powerful potions to use against the dark forces.
Well, perhaps in the fanfiction, they are all entered into a magical tournament. Harry, being the young and brave one, Snape with his vast knowledge of magic, and Lucius with his family's resources. At first, they are rivals in the tournament but then realize that there is an outside force trying to manipulate the outcome for evil purposes. So they join forces. Or it could be that a powerful dark magic spell has been cast over Hogwarts, and only the combined magic of Harry, Snape and Lucius can break it. They start off distrustful but as they work together, they form an unlikely alliance.