Maybe Hedwig and Snape are tasked with a special mission in the afterlife. They have to work together to solve a mystery that is related to the wizarding world they left behind. This could involve characters like Dumbledore or Voldemort in some way, perhaps even uncovering secrets that were never known in life.
One plotline could be that Snape is initially confused in the afterlife and Hedwig appears to him, bringing a sense of calm. They start to communicate in a way that was not possible in life.
It could be a story where Hedwig serves as a sort of guide for Snape in the afterlife. Maybe she shows him the good he did that was overlooked in life.
One possible plotline could be the characters in the afterlife having to atone for their sins. For example, characters like Joffrey might face some sort of punishment or redemption arc in the afterlife realm. Another could be the great heroes of Westeros coming together to fight against some new threat that exists even in the afterlife. Maybe they have to stop a dark force from spreading chaos among the souls. And perhaps the Starks and Lannisters could put aside their differences and work towards a common good in this afterlife scenario.
Maybe in a fanfiction, Harry could be framed for something he didn't do, and Snape, believing the false accusations, smacks him in a moment of anger. This could then lead to a series of events where Harry tries to prove his innocence and Snape has to come to terms with his hasty action. Another plotline could be that Snape is under the influence of a dark spell that makes him act out of character, and Harry just happens to be in the wrong place at the wrong time and gets smacked.
One possible plotline could be that Harry discovers Snape's memories early on. Overwhelmed by the truth of Snape's love for his mother and his selfless sacrifices, Harry hugs Snape as a sign of immediate forgiveness and gratitude. Another could be in a post - war scenario where Snape is still alive, and Harry, now a more mature wizard, reaches out to Snape to heal old wounds.
There could be a plot where Snape's muteness is a secret that he tries to hide from everyone at Hogwarts. The story could be about how he manages to teach Potions and be a double agent for Dumbledore all while keeping this secret. Or perhaps a plot where his muteness is a magical experiment gone wrong, and the story is about his journey to reverse it. Along the way, he might discover new aspects of magic and his own identity that he never knew before.
In some 'Snape slave to Harry fanfiction', the plot might start with a prophecy or a magical bargain. Maybe a seer predicted that only with Snape as Harry's servant could a great evil be defeated. So, Snape, bound by this fate, has to follow Harry's commands. Along the way, they face many challenges together. Harry has to deal with the power imbalance and Snape has to struggle with his pride. Their relationship evolves from one of forced servitude to a more complex bond of respect and cooperation as they fight against the forces of darkness.
Perhaps in some 'harry marries snape fanfiction', there could be a magical accident that binds their fates together. At first, they resist the connection, but as they get to know each other better, they find common ground and fall in love, leading to marriage. This could involve a lot of emotional turmoil and self - discovery for both characters.
Maybe Hermione is injured while exploring some dangerous magical ruins. Snape is the only one around with the knowledge and power to heal her. As he heals her, they start to have deep conversations about magic, life, and their respective pasts, which in turn builds a connection between them.
One possible plotline could be that Snape accidentally discovers Harry is extremely ticklish and uses it as a form of mild punishment when Harry misbehaves in Potions class. For instance, if Harry forgets an ingredient or causes an explosion.
One possibility is that in the afterlife, Snape finally finds peace. He no longer has to hide his true loyalties or endure the scorn of those who misjudged him. He might be reunited with Lily, and they could have the conversations they never had in life. He could also meet with Dumbledore again, and they could discuss all the secrets and sacrifices that were made during the war.