A possible plot could be that Kane and the player get transported to an alternate dimension. In this new world, they have to find a way back while also dealing with the strange and dangerous things in this dimension. They might encounter versions of themselves or other characters from the game with different personalities.
One idea could be that the player and Kane have to team up against a new, powerful enemy that neither can face alone. They start off distrusting each other but as the story progresses, they learn to rely on one another's skills.
Perhaps the player discovers a dark secret from Kane's past that Kane has been trying to hide. This could lead to a tense relationship where the player has to decide whether to expose Kane or keep the secret and help him deal with it. For example, it could be something related to a past mission gone wrong and Kane's role in it.
One idea could be a story about a group of survivors who discover a hidden underground bunker filled with ancient zombie - fighting weapons. They have to figure out how to use these weapons while being chased by hordes of zombies.
Another plot idea is that a team of soldiers accidentally time - travels while fighting zombies. They end up in an earlier era of the zombie outbreak and have to use their knowledge of future events and modern weaponry (which they still have) to change the course of the apocalypse. They might meet younger versions of characters they knew in their own time and have to convince them to follow a different path to prevent the spread of zombies.
One idea could be a story about a Spectre that gains self - awareness and tries to escape the control of its creators. It could embark on a journey to find a place where it can exist freely, facing various challenges along the way.
One idea could be that the shinobi have to use their unique jutsu to fight off the zombies. For example, Naruto could use his shadow clones to distract the zombies while Sasuke uses his fire jutsu to burn them. Another idea is that the zombies are actually the result of a failed experiment by Orochimaru. He was trying to create an immortal army but instead created these undead creatures.
One idea could be exploring the backstories of the minor characters more in - depth. For example, the soldiers who are part of the squad but don't have much screen time in the game. Another could be creating an alternate ending where the events of the game take a different turn, like the main villain actually succeeding in their initial plan but then the heroes have to find a new way to reverse it. And a third idea might be to write a fanfiction from the perspective of the enemy forces, showing their motives and what they think during the battles.
One plot idea could be Marlton and Misty getting separated from the rest of the group during a mission. They have to rely on each other to survive in a hostile environment. Maybe they discover a hidden enemy base while trying to find their way back. Another idea is that they find an ancient artifact that has some sort of power, and they must figure out how to use it to their advantage. A third plot could involve them having to deal with a traitor within their own ranks who is trying to undermine their mission while they also deal with their growing relationship.
Maybe an Anbu agent who has a special ability that no one in the village knows about. He or she is sent on a mission related to Orochimaru. During the mission, the agent starts to question the morality of the Anbu's actions as they often involve killing without trial. This could lead to a character - driven story about loyalty, morality, and self - discovery.
One interesting plot could be a secret mission within Hogwarts where a group of students form a black ops - like team to uncover a hidden threat that the teachers are unaware of. They might use magic in unconventional ways, like combining spells for stealth and detection.
Show them sharing common goals. For example, if they are both aiming to take down a big bad in the game world, they will start to respect each other's abilities. Simple things like the player covering Kane in a firefight and Kane returning the favor later can build trust.
One good storyline could be Kane's origin story. Explore how he became the character he is in Black Ops 3. Maybe he had a difficult childhood that led him to a life of military service. Another could be a post - game scenario where Kane has to deal with the aftermath of the game's events. He might be struggling with PTSD and trying to find his place in a world that's still in chaos.