If Snape goes missing, Hogwarts would be in chaos. His students would be worried and confused. The other teachers would have to take over his classes, but no one could replace his unique teaching style.
In fanfiction, his friends or former associates might go on a quest to find him. This could lead to all sorts of adventures. They could discover new places, meet new characters, and uncover secrets about Snape that were previously unknown. Maybe they'll find out that he has a family he was protecting all along, and that's why he disappeared.
One possibility could be that he has gone into hiding to protect a secret. Maybe he discovered some dark magic plot and has to keep himself away from the wrong people until he can figure out how to stop it.
One possibility is that Naruto gets transported to the world of Harry Potter where he meets Snape. Naruto's energetic and positive attitude could clash with Snape's brooding nature. However, they might find common ground in their loyalty to their respective friends and causes. Naruto could show Snape the value of perseverance in a different light, and Snape could introduce Naruto to the complex world of potions and magic.
He could have a magical mishap. For example, a spell meant for the decorations goes wrong and lands on him, making him do something silly like dance uncontrollably. It would be a humorous take on his usually serious character.
There could be a plot where they are forced to work together on a project. Snape initially resents it, but as they collaborate, he sees Hermione's determination and begins to fall for her. However, he has to deal with the fact that she is a Gryffindor and he has his own reputation to uphold. This creates a lot of drama and tension in the story.
Perhaps in this 'Boruto goes missing fanfic', Boruto is lured away by a mysterious figure who claims to have information about his future or his father Naruto's past. He follows this figure without thinking, only to find himself in a strange and dangerous place. His disappearance then sets off a chain of events in the village. People start to suspect that there might be a traitor among them who helped Boruto disappear. His teammates, like Sarada and Mitsuki, would then start their own investigation to find him, facing not only external threats but also internal doubts and suspicions within the village.
Perhaps Snape could help Albus Severus come to terms with his family legacy. Albus Severus is named after two great wizards, Albus Dumbledore and Severus Snape. Snape could share his own experiences of being in the shadow of great names and how to carve out one's own identity in the wizarding world. This encounter could be a very emotional and character - building moment for Albus Severus.
Well, Albus could finally understand Snape's true nature. Maybe he discovers the sacrifices Snape made for his family. He might apologize for any wrong assumptions he had about Snape in the past.
Bellatrix Lestrange could also be a character who interacts with Snape. If Snape goes back far enough, he might try to influence Bellatrix's path and keep her from becoming such a devoted Death Eater. This could have a major impact on Voldemort's power and the overall balance of the wizarding world.
In some fanfiction, this could happen through a powerful spell gone wrong. Maybe Snape was attempting a complex transfiguration spell for some secret reason, like protecting Harry from a dark magic threat in a very unorthodox way. And the result was Harry being turned into a shifter.
One way this could occur in fanfiction is through a magical mishap. Maybe a spell goes wrong and binds their fates together in an unexpected way. They are then forced to navigate this new relationship. Snape, who has always been a complex character, might find in Harry a new purpose or a chance at redemption. Harry, on the other hand, could see Snape in a different light and over time, their relationship could transform into a romantic one, leading to marriage as a logical conclusion in the fan - created story.