Another interesting concept is that a group of survivors from Dead by Daylight accidentally stumble into Slenderman's forest. They have to use their survival skills from the game, like hiding and fixing things, to escape Slenderman's clutches. The survivors could also have different reactions based on their in - game personalities. Some might be more brave and try to fight back, while others would be more timid and focus on hiding.
One idea could be a crossover where the Slenderman becomes a new killer in Dead by Daylight. He could use his teleportation and mind - controlling abilities to hunt down survivors. For example, he might make survivors hallucinate the location of generators or exits, leading them astray.
You could do a crossover with 'Castlevania'. The gothic horror elements of 'Castlevania' would blend well. Dracula could be a powerful killer, and the heroes from 'Castlevania' could be survivors. The survivors might have new abilities like using holy water or magic spells against the killers. It would also be interesting to see how the 'Dead by Daylight' maps would be transformed with the addition of 'Castlevania' - like architecture and elements.
One idea could be Naruto being a survivor with his unique ninja skills to outwit the killers. For example, he could use his shadow clone jutsu to confuse the killer and lead them astray. Another could be that some of the Naruto villains are the killers in the Dead by Daylight world, like Orochimaru with his snake - like abilities making him a terrifying and sneaky killer.
You could also create a plot where the Slenderman is not the typical villain. Maybe he's been lured into the Dead by Daylight world against his will. He initially attacks the survivors because he's disoriented and scared. A survivor with empathic abilities realizes this and tries to communicate with Slenderman. They form an unlikely alliance to find a way to get Slenderman back to his own world and also to escape the clutches of the Entity. This would be a very different take on the usual horror dynamic in Dead by Daylight.
One idea could be that Slenderman and Enderman are from different dimensions but are somehow connected by a mysterious force. They start to communicate telepathically and form an alliance to protect their shared secrets from other mobs in the Minecraft - like world. Another plot could involve Slenderman being lost in Enderman's realm and Enderman helping him find his way back, while they both learn about each other's powers along the way.
Maybe they start as rivals, constantly trying to outdo each other in terms of scaring mortals. But then they realize that together they can create a much more terrifying world. So they start working together, with Zalgo spreading madness and Slenderman preying on the fearful minds.
One plot idea could be that Dwight, being the leader - type in the survivors' group, tries to understand the Trapper's motives. Maybe he gets caught in a trap but instead of panicking, he tries to reason with the Trapper. The Trapper, initially hostile, starts to question his own actions due to Dwight's calmness.
Some fanfictions might center around the idea of the survivors finding a way to break free from the Entity's control once and for all. It could involve a lot of mystery and suspense as they discover secrets about the Entity's realm and use their combined skills and knowledge to try and escape. Maybe they find a powerful artifact within the realm that could be the key to their freedom.
One idea could be that Slenderman somehow enters the wizarding world of Harry Potter. Maybe he's drawn by the powerful magic there. He could start causing strange disappearances in the Forbidden Forest, and Harry and his friends have to figure out how to stop this new, otherworldly threat using both their magic skills and their knowledge of the wizarding world's secrets.
One idea could be that Jeff the Killer becomes an apprentice of Slenderman. He learns the more supernatural and strategic ways of hunting from Slenderman. Another could be a story where they have to team up against a common enemy, like a powerful group of demon hunters who are after both of them. Or perhaps a plot where Jeff the Killer starts to question his own murderous ways after spending time with Slenderman, who has a more calculating and long - term approach to his actions.
One interesting idea could be the exploration of their contrasting personalities. Slenderman is often depicted as this mysterious, otherworldly being, while Jeff the Killer has his own brand of insanity. In the fanfiction, they might interact in ways that bring out new aspects of each other's characters, like how Slenderman's calmness could either soothe or further enrage Jeff.