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.
A possible plot is that there is a prophecy about Slenderman and Enderman uniting to stop an evil that threatens to destroy their existence. They initially distrust each other but as they face various challenges together, they come to respect and rely on one another. For example, they might have to battle a powerful group of wither skeletons that are after a magical artifact that only their combined powers can protect.
Well, they could be rivals at first. Enderman is known for its teleportation and pick - up abilities, and Slenderman has his own set of spooky powers. They could compete to see who is more powerful in their respective domains. But then, they discover that there is a new threat emerging, like a strange dark magic that is corrupting the land. To stop it, they have to put aside their differences and combine their powers. This could lead to some really cool action scenes where they use their unique abilities in tandem.
A plot could revolve around an Enderman getting injured near a Creeper's lair. The Creeper, instead of attacking, decides to help the Enderman heal. This act of kindness starts a friendship that then grows into a unique partnership as they face various challenges in their Minecraft environment.
One idea could be that the reader is a new adventurer in the Minecraft world and stumbles upon an Enderman who is different from the others. Instead of being hostile, it seems curious about the reader. Another could be a story where the reader has the ability to communicate with Endermen and tries to bridge the gap between them and the other mobs in the game. Or perhaps the reader gets trapped in the End dimension and an Enderman becomes their unlikely protector.
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 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.
A possible plot could be that Jeff has a dream where he meets Slenderman. In the dream, Slenderman offers him a chance to become even more powerful. Jeff is tempted and when he wakes up, he starts to search for Slenderman in the real world, leading to a journey full of strange encounters and self - discovery.
One idea could be that the Enderman and Creeper form an unlikely alliance. The Enderman could use its teleporting ability to move the Creeper around the Minecraft world to strategic locations where they can both fend off other mobs. For example, they could work together to protect a village from a horde of zombies. The Creeper could explode to take out large groups, while the Enderman teleports in to pick off any stragglers.
Slenderman's ability to be invisible or blend into the shadows could be combined with Enderman's teleportation. For example, Slenderman could hide in the shadows while Enderman teleports them both quickly away from danger. Or Enderman could teleport to a location and then Slenderman could use his spooky presence to create a diversion while Enderman steals an important item.
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.
For a Slenderman Harry Fanfic, a great plot might be that there's a prophecy about Harry and Slenderman. The prophecy states that only Harry can defeat Slenderman in a final battle of magic. So, Harry starts to have strange visions of Slenderman and has to train himself in new and dangerous forms of magic to be able to stand a chance. Along the way, he meets some new magical creatures that are either helping or hindering his quest. Also, the Ministry of Magic doesn't believe Harry about Slenderman at first, thinking it's just another one of his wild stories, which adds to the drama and difficulty of his task.
One idea could be that the Slenderman somehow enters the RWBY universe during a Grimm attack. The characters of RWBY initially mistake him for a new type of Grimm. But as they start to investigate, they realize he has very different and more sinister powers compared to the Grimm.