Maybe Naruto is trying to find a way to bridge the gap between different races in his own world. So, he uses his knowledge of ninjutsu and some sort of ancient magic he discovers to create the Faunus. And then the story could be about how the Faunus adapt to their new existence and how Naruto helps them fit into the world.
I'm not sure of specific 'Naruto creates the Faunus' fanfictions off the top of my head. But you can try looking on popular fanfiction websites like Archive of Our Own or FanFiction.net. Search for the key phrase 'Naruto creates the Faunus' and browse through the results. Some might be really interesting with unique plotlines and character developments.
One idea could be that Naruto discovers a hidden bloodline within himself that gives him the ability to control time on a small scale. He could use this new power to outwit his enemies during battles. For example, he freezes time briefly to dodge a powerful attack and then counterattacks while his opponent is still in a state of confusion.
In the 'naruto creates nightmares fanfic', it might be that Naruto enters a strange dimension during a mission. In this dimension, his thoughts and emotions take a dark turn and start manifesting as nightmares that not only affect him but also seep into the real world, affecting his comrades. As he struggles to break free from this dimension, the nightmares keep spreading and causing chaos.
One idea could be a faunus with the traits of the Nine - Tailed Fox being an outcast in the ninja world because of the power and fear associated with it. They struggle to find their place while also having to control the fox - like instincts within them.
Perhaps the Akatsuki members are using baccarat as a means to gather funds for their evil plans. Naruto and his team discover this and try to stop them by interfering with the baccarat games. They might have to learn the rules of the game quickly to be able to do so. The story could involve a lot of strategic battles within the context of the baccarat games, like using jutsus to affect the outcome of the card draws.
Well, in such a fanfiction, Naruto might discover a new chakra ability that allows him to create Kirin. He could be in a tough battle where his usual jutsus aren't enough. So, he taps into some hidden potential within himself to form Kirin. Maybe he combines his own wind - style chakra with some newfound lightning - style chakra he got from a special training or encounter.
One possible plot could be that Naruto, using his unique skills and leadership, unites the various ninja clans under his banner to form an empire. He might introduce new forms of governance that combine ninja traditions with more democratic ideals, ensuring equality among all citizens regardless of their ninja abilities.
If Naruto creates Grimm fanfiction, perhaps he would imagine himself as a Huntsman in the Grimm world. He might use his shadow clones to outnumber the Grimm. His ninja skills like the Rasengan could be transformed into some sort of super - attack against the Grimm. Also, he could bring the concept of chakra into the Grimm universe and have the characters use it to fight the dark creatures.
One idea could be that Naruto creates his own village as a place of true peace and equality. He invites all those who have been marginalized or ostracized from other villages to join. His village would have unique training methods that combine all the ninja arts he has learned from different places, like the shadow clone jutsu combined with Sand Village's puppet techniques for a new form of combat.
One idea could be that Naruto creates his sword using his chakra. He might infuse it with the power of his Nine - Tails chakra, making the sword have a unique orange glow. This sword could have the ability to cut through any jutsu, like a hot knife through butter.