You could also write a fan fiction about the Black Company encountering a completely new and powerful enemy. Maybe a magical being from a far - off land that forces them to adapt their tactics and learn new skills in order to survive.
A cool plot for The Black Company fanfiction could be a story about a new recruit who has some special power that no one in the company has ever seen before. This power could either be a great asset or a source of suspicion among the other members. Or you could write a plot where the company has to face an enemy that is not from their usual foes, like a supernatural force that they don't understand at first. It could also be interesting to write a story about the relationships within the company, like a love story between two members that has to be kept a secret because of the company's rules.
One idea could be exploring the backstories of the characters in more depth. For example, delving into the past of the player - controlled character, their training, and what led them to be part of the Black Ops 3 unit. Another plot could involve a mission that goes horribly wrong and the team has to fight against their own side that has been corrupted by some new enemy technology. Or perhaps a story about a character who discovers a hidden conspiracy within the military that the Black Ops 3 operations are actually covering up.
One idea could be exploring a world where the social credit system in Black Mirror becomes a global phenomenon. How would people adapt? Another could be a story about a character who discovers a way to reverse the effects of the memory - altering technology. And perhaps a fan fic where a group tries to overthrow the dystopian regime created by some of the Black Mirror tech.
One idea could be a story where the Mandalorian has to team up with an old enemy to fight a new, greater threat. Maybe a powerful Sith Lord emerges and they have to put aside their differences.
One idea could be exploring a different origin for Toothless. Maybe he was part of an ancient dragon tribe that was thought to be extinct. Another could be a story where Hiccup discovers a new dragon species that has unique abilities and forms an alliance with them. A third idea is a time - travel fan fiction where Hiccup goes back in time to prevent a great dragon war from ever starting.
A great plot for Warframe fan fiction could be a Tenno getting trapped in a parallel dimension where the rules of the Origin System are all messed up. They have to find a way back while dealing with strange versions of familiar enemies. Or perhaps a story about a Tenno who discovers a hidden Orokin vault that contains not only powerful weapons but also a secret that could change the balance of power in the Origin System. Also, a plot about a Tenno's struggle to control a newly acquired and extremely powerful Warframe that has a mind of its own could be really engaging.
Well, you could have a survivor fan fiction where a contestant has a hidden skill, like being able to communicate with animals on the island. This could give them an edge in finding food and avoiding danger. Or perhaps a story where there's a traitor within the group, someone who is secretly working with the show's producers to create more drama. Also, a plot where the survivors find a map that leads to a hidden part of the island with a bountiful supply of food and shelter.
One idea could be that the Ghostbusters discover a new type of ghost that can possess technology. So they have to find a way to stop it from taking over all the electronics in the city. It would be a race against time as the city starts to descend into chaos with machines going haywire.
One idea could be a story where a minor character from the game gets a chance to become a hero. For example, a low - level soldier who discovers a hidden power within himself and uses it to save his comrades during a crucial battle.
One interesting plot idea could be exploring what would happen if Aladdin's three wishes had unforeseen consequences that affected not just him but the whole city. For example, a wish for wealth might lead to an economic imbalance.