In a 'Legend of Zelda Keeper of Darkness Fanfiction', it could be that the Keeper of Darkness is an ancient entity that was once sealed away but has now been accidentally released. The story could center around a young adventurer who discovers the truth about the Keeper. This adventurer then has to learn the ways of the ancient heroes, perhaps by finding old scrolls or talking to the sages. As they progress, they realize that the key to defeating the Keeper of Darkness lies not just in physical strength but also in understanding the true nature of light and darkness in the Zelda world.
Another possibility is that it could be Zelda herself. She is a powerful character with magic abilities. She could be the main character trying to use her powers to stop the Keeper of Darkness from plunging Hyrule into eternal darkness.
It could be about Link ending up in Equestria and teaming up with Twilight Sparkle to fight a new evil that threatens both their worlds. Maybe Ganondorf has found a way to enter Equestria and is causing chaos, and Link uses his combat skills while Twilight uses her magic to drive him out.
Well, one possible plot could be that Sailor Moon and her friends get transported to the world of Legend of Zelda. They could team up with Link to fight against a common enemy like Ganon who has somehow allied with the Dark Kingdom from Sailor Moon. Sailor Moon could use her powers to heal Link when he gets injured in battles, and Link could teach the Sailor Scouts some of his combat skills.
One possible plot could be that Death, as an entity, has somehow entered the world of Legend of Zelda. Maybe it's a dark curse that has befallen Hyrule. Link then has to find a way to either defeat Death or make a deal with it to save his land and the people he loves. For example, Death could be stealing the souls of the villagers, and Link has to journey to the underworldish realm where Death resides to stop it.
One possible plot could be that Link finds himself in the Marvel universe. He teams up with Spider - Man to stop Ganondorf, who has made a deal with some villains in the Marvel world to gain more power. Link uses his sword skills and Spider - Man uses his webs and agility to fight off Ganondorf's minions and ultimately face the big bad himself.
One interesting plot could be that the heroes from The Legend of Zelda, like Link, find themselves in the world of RWBY. Link might have to team up with Ruby and her friends to fight a new common enemy that is a fusion of the dark forces from both universes. For example, Ganon's magic combines with Grimm energy to create a super - powerful and menacing foe.
Well, it could start with Naruto being corrupted somehow, perhaps by dark magic. He then travels to the Zelda universe. He could use his ninja skills against the heroes of Zelda. He might try to take over Hyrule Castle, thinking it has some sort of power that can make him even more powerful in his own world. And along the way, he would face off against Link, Zelda, and other characters from the Zelda series. There could be a big showdown where the fate of both the Naruto world and the Zelda world hangs in the balance.
One possible plot twist could be that the two Links are from different timelines and their meeting causes glitches in the fabric of the Zelda universe. For example, the meeting might disrupt the natural flow of events, leading to unexpected changes in the locations of dungeons or the behavior of enemies.
One possible plot could be that the main character, who has the abilities of both Naruto and Link from Legend of Zelda, finds himself in a world where he meets various female characters from both universes. They are initially wary of him but as he helps them with different challenges using his unique skills, they start to develop feelings for him. For example, he might use Naruto's shadow clone jutsu to help in a large - scale battle in the Zelda world, impressing the female warriors there.
Well, it could be about a scenario where Naruto is banished from his own world and somehow ends up in the world of The Legend of Zelda. Maybe he has to adapt to the new rules, magic, and creatures there. He could use his ninja skills in interesting ways in the Zelda universe, like using his shadow clone jutsu to solve puzzles or fight enemies.