Some fanfictions might focus on his relationship with Dumbledore. They could show that in his suicidal state, Snape blames Dumbledore for using him and for the overall situation he's in. This is different from the canon where he was loyal to Dumbledore's cause, but in these stories, his loyalty might be more grudging and the stress of their relationship could be a factor in his suicidal thoughts.
Regarding his relationship with Harry, in these fanfictions, Snape's suicidal feelings could be tied to his complex feelings towards Harry. Instead of the somewhat hidden protectiveness in the original story, it could be shown as a source of great internal conflict. He might see Harry as a constant reminder of Lily and his own failures, and this could be a significant part of his downward spiral in the fanfiction.
Sick fanfictions also often explore Snape's relationships in a different light. His relationship with other professors might become more friendly or at least more understanding. Since he's sick, they might come to his aid or show concern. This is different from the normal somewhat aloof relationships he has in the books. And his relationship with the students can also change. Some students might feel sympathy for him and start to respect him more, which changes the dynamic between them.
In romantic relationships in fanfiction, Snape can be quite badass. He might be very guarded at first, not easily giving in to his feelings. But when he does, he's all in. He'll protect his love interest from any danger, whether it's from dark wizards or from the prying eyes and gossiping tongues of Hogwarts. He uses his skills and knowledge to keep them safe, and if anyone tries to come between them, he'll use his wit and magic to drive them away.
In the books, Snape's power is often shown in a more subdued way. In fanfictions, his potions skills might be exaggerated. For example, he could create potions that can bring the dead back to life. His Occlumency is also depicted more dramatically. In fanfictions, he can use it to control minds rather than just protect his own. Also, his role as a double agent is sometimes made more central, with his power to deceive Voldemort being enhanced to superhuman levels.
In many of these fanfictions, Snape is often portrayed as a complex and misunderstood figure. He is shown as having a deep - seated sense of loyalty, whether it's to Hogwarts or to the memory of Lily. For example, in some stories, he acts as a sort of guiding spirit for Albus Severus, using his past experiences to help the young Potter navigate the challenges at school.
Often, fanfictions show a very strained relationship between them. Given Tobias's likely abuse of Severus in the original story, many fanfictions expand on Severus's internal struggle with his father. For instance, Severus might be constantly haunted by memories of his father's drunken rages.
In Ravenclaw fanfiction, Snape might be depicted as having a different aesthetic. Instead of the typical Slytherin dark robes, he could be dressed in more muted blues or silver - grey, colors associated with Ravenclaw. His personal space, like his office or living quarters, could be filled with Ravenclaw - like symbols and items. His teaching style may also change, becoming more in line with Ravenclaw's open - minded approach to learning, encouraging students to question and explore different magical theories rather than just following the textbook.
They often show him as a deeply conflicted and damaged individual. His past experiences, like his difficult childhood and the complex relationships in his life, are used to explain his tortured state. For example, his unrequited love for Lily might be explored in more depth, and how that has tortured him over the years.
One common theme is his unrequited love for Lily. In many of these fanfictions, his love for her that was never fully realized is a driving factor towards his suicidal tendencies. His sense of loss and failure in protecting her is so overwhelming that it makes him question his own existence.
In fanfiction, James Potter is sometimes portrayed as a more complex character than in the original books. He might be shown as having deeper regrets about his bullying of Snape. On the other hand, Severus Snape can be presented as even more of a tragic figure, with his love for Lily being explored in more detail. His bitterness towards James can also be magnified.
If he meets Lily in the afterlife, their relationship could become more of a true friendship. Without the complications of James Potter and the war, they could finally understand each other on a deeper level. Snape could let go of his unrequited love and instead cherish the bond of friendship that was always there beneath the surface.