Obviously, Harry Potter and Severus Snape are the main characters. Harry is the one who is forced into this situation, and Snape is the one he has to please. But other characters like Hermione and Ron could also be involved. They might try to help Harry out of this difficult situation or be affected by the consequences of Harry's actions to please Snape.
Perhaps in the fanfiction, Harry is magically bound to please Snape in academic tasks. So, he has to study extra hard in Potions class and other subjects Snape is involved in. This might result in a transformation of their relationship, from animosity to a grudging respect as Snape starts to see Harry's efforts.
Harry would probably be quite resentful at first. He might think Snape is just being his usual unfair self. So, he would be sulky and do the tasks reluctantly.
One reason could be a misfired spell by another character. For example, if a young wizard was experimenting with a transportation spell and it backfired, it could accidentally force Harry to be attached to Snape in this 'ride' situation. Another reason might be a plot by a dark wizard who wants to see chaos at Hogwarts. They figure that forcing Harry and Snape together in this strange way would disrupt the normal order of things.
As time goes on, Harry could start to explore what it means to 'please' Sirius. He might recall their past relationship, the things Sirius likes and dislikes, and try to use that knowledge to his advantage. He may also feel a sense of loyalty towards Sirius that, despite the odd circumstances, makes him more accepting of the situation. For example, he might remember Sirius' love for adventure and try to engage in some magical adventures with him in a way that 'pleases' him.
Snape's reaction could also be one of extreme caution. He would be constantly on guard, worried that Harry might discover some of his secrets or that Voldemort's supporters might target Harry while he's in his care. So he would be very vigilant, but this might also lead to some over - the - top reactions when Harry does something even slightly out of the ordinary. However, over time, this vigilance could turn into a form of care as he gets used to Harry being around.
Yes, it's possible. Fanfiction can take many different turns. Some writers could be exploring the idea of forced proximity between Harry and Snape to build a different kind of relationship dynamic. Maybe it's about Harry being magically or situationally forced onto Snape's bed as a means to start a conversation or resolve some long - standing misunderstandings between them, without any improper undertones.
Well, Harry could be forced to clean the Potions classroom during detention. Snape might make him scrub every cauldron by hand while muttering about how clumsy Gryffindors are. Harry might accidentally spill a potion ingredient, which makes Snape even angrier and gives him more tasks to do, like sorting out all the potion ingredients in the store cupboard.
Finding 'Harry forced Mary Snape' fanfiction could be a bit of a challenge. Since it's not a mainstream concept within the Harry Potter fan community, it may not be as easy to come across as more popular fanfiction themes. Some fanfiction authors might be more inclined to write about the relationships and events that are more closely related to the original books, like the relationship between Harry and his friends or the battles against Voldemort. But that doesn't mean there isn't a story out there with this particular concept. You could also check some niche Harry Potter fanfiction communities or forums where fans might discuss or share such unique stories.
In some fanfictions, Snape might use his advanced knowledge of potions to create a special concoction to heal Harry. He could draw on his skills in Herbology as well to find rare ingredients for the potion.