Well, sometimes in these fanfictions, a common plotline is the reincarnated character trying to improve Snape's relationships. They might work on mending his relationship with Lily, perhaps by being more open and less bitter. Another aspect could be the character using Snape's position at Hogwarts to influence the next generation of wizards in a more positive way. For instance, they could be stricter with the students who show signs of dark magic tendencies, but also more nurturing to those who are bullied. And of course, there could be a plotline where the character has to face the same challenges Snape did, like dealing with Voldemort's return, but with a new perspective and modern knowledge.
One interesting plotline could be the protagonist using Snape's knowledge of potions to create new and revolutionary brews. For example, they might discover a potion that can heal previously incurable dark magic wounds. Another plotline could involve the character trying to change Snape's fate in the wizarding world. They could attempt to prevent Snape from getting involved in certain dangerous or tragic events, like his involvement with the Death Eaters in his youth. Also, there could be a plot where the reincarnated character uses Snape's occlumency skills to uncover hidden secrets in Hogwarts that were previously unknown.
Perhaps a plot where Severus discovers his demigod heritage and has to balance it with his life at Hogwarts. He could struggle with how to use his new - found powers without drawing too much attention, while also dealing with his complex relationships with other characters like Harry Potter.
One interesting plotline could be exploring Snape's early interactions with the Marauders. Maybe it shows how his enmity with them truly began. For example, it could focus on a particular incident in their school days that was a turning point.
Perhaps a plotline where Snape's heart leads him to question his loyalty to Voldemort. As he becomes more in touch with his emotions, he realizes the true horror of the Dark Lord's actions. This could lead to him secretly working against Voldemort in a more direct way than in the original story. He may also find himself in the middle of a moral dilemma as his new - hearted self clashes with his past actions.
One interesting plotline could be Harry growing up with Snape's guidance and inheriting his potions skills at an early age. He might have a different dynamic with the other Hogwarts students, being more of an outcast due to his connection to the often - misunderstood Snape.
One interesting plotline could be Snape going back and trying to prevent the death of Lily Potter. He might use his knowledge of the future to change certain events that led to her demise.
Some fanfictions have a plotline where the OC is a healer who is called to Hogwarts to deal with an epidemic of a magical illness. Snape is initially skeptical of her methods, but as she starts to make progress, he becomes more interested in her work and in her as a person. This kind of plotline allows for a lot of character development for both Snape and the OC, and also shows the different aspects of the wizarding world's medical and magical practices.
One interesting plotline could be Severus Snape as the Dark Lord secretly working to undermine the true evil forces from within. He might be using his double - agent skills in a new way, playing both sides not just between the Order of the Phoenix and Voldemort, but among different factions of dark wizards. For example, he could be preventing more heinous acts that would lead to the total destruction of the wizarding world while still maintaining his dark facade.
One interesting plotline could be Snape trying to protect his family from the dark forces in the wizarding world. Since he has a complex past, he might be worried about his family being targeted because of his associations. For example, his enemies from his Death Eater days could try to harm his family to get back at him.
One common plotline is Snape being sorted into Ravenclaw instead of Slytherin. This leads to a whole new set of relationships and rivalries. For example, he might have a friendly rivalry with a fellow Ravenclaw over the top grades in Potions. Another plotline could be Snape uncovering a long - lost Ravenclaw secret. Maybe it's a hidden spell or a piece of Ravenclaw history that has been lost for centuries and his inquisitive nature drives him to solve the mystery.
One possible plotline could be that Moody discovers Snape is in a dangerous situation due to some dark wizard's plot against him. Maybe Snape is being framed for a crime he didn't commit, and Moody, with his Auror skills and knowledge, believes in Snape's innocence. He then uses his resources and magic to rescue Snape from an ambush or a false arrest. Another plotline could involve Snape being held captive by Death Eaters, and Moody, despite their past differences, decides to rescue him because he realizes Snape is a crucial part of the fight against Voldemort.