One common scenario is when Snape is in a vulnerable situation, like during a DADA class. His boggart - his father - might appear and start berating him for being a wizard or for being different. This shows Snape's insecurities about his identity.
Sometimes, in fanfiction, Snape might be in a dark and lonely place, and his boggart (his father) emerges. His father could be shown as drunk and violent, which reflects on Snape's fear of his father's abuse and his inability to escape that part of his past. This can be used to add more depth to Snape's character and his backstory within the fan - created narrative.
In some fanfictions, Snape's boggart being his father might be due to the abusive nature of their relationship in the original lore. His father was a Muggle who perhaps made Snape's childhood miserable, so it's a deep - seated fear that haunts him even in fan - created stories.
One common scenario is when Draco is in trouble with other students, especially Gryffindors. Snape steps in and defends Draco, using his position as a teacher to put the other students in their place. For example, if Harry Potter and his friends are confronting Draco about something, Snape would quickly come to Draco's side.
One common scenario is after a fight with Voldemort or his followers. He might get injured and start limping as a result. Another could be when he's in a hurry to save someone, like Harry Potter perhaps, and in the process he injures his leg.
One common scenario could be in the face of other students' bullying. Snape might subtly step in and stop the bullies without making it too obvious. For example, he could give the bullies extra assignments or detention, which would indirectly protect Hermione from their taunts.
In fanfiction, Severus Snape's boggart could be the lifeless body of Lily Potter. Since he loved her deeply and her death was a great tragedy for him. It would represent his ultimate fear of losing her all over again, even in the form of a boggart.
A common boggart scenario in fanfiction is related to the characters' insecurities. For Harry, it could be that the boggart shows him as the cause of all his friends' misfortunes, emphasizing his fear of being a burden or a danger to those he loves. This can add more depth to his character and explore his self - doubts further.
One common scenario could be that Harry is caught sneaking around the Slytherin common room or stealing potions ingredients from Snape's stores. So, Snape and Draco might make him do extra detention tasks like scrubbing the cauldrons for hours without magic. Another situation could be if Harry is suspected of cheating in a Potions exam. Draco might report it to Snape, and they could punish Harry by making him redo all his Potions experiments from the semester.
There are fanfictions where Snape's boggart takes the form of a powerless version of himself. This could explore his insecurities about his own strength and status. Maybe in the story, he has to face this boggart in a life - or - death situation and it forces him to reevaluate his self - worth.
Often, Snape will single out Harry in front of the whole class. He might publicly criticize Harry's work or attitude. For example, when Harry is assigned a group project in Potions, Snape might give Harry extra tasks or set higher standards just for him. And during exams, Snape could be extra strict when grading Harry's papers.
Snape could also assign Draco to do research on a particular dark magic item or spell. This would be a punishment as it would involve a lot of time and effort, and also expose Draco to the dangerous side of magic that Snape wants him to be cautious about. It also gives Draco a chance to learn more about the consequences of misusing magic.