In a crossover with the DC universe, Superman could be an interesting character to pair with Master Chief. They are both strong and have a sense of justice, but their powers and methods are very different. Another good one could be Batman. The contrast between the high - tech Master Chief and the more detective - style Batman would make for an exciting story. In the Marvel universe, Captain America would be a great pairing. Their leadership skills and commitment to their causes could create some great interactions.
One idea could be a crossover with the Star Wars universe. The Master Chief could find himself on a planet in the Star Wars galaxy, facing off against Sith or Jedi. Maybe he teams up with some of the Rebel forces. Another idea is a crossover with the Warhammer 40K universe, where his Spartan skills are put to the test against the various threats in that dark and gritty setting. A third idea could be a crossover with the Mass Effect universe, interacting with the different alien species and getting involved in their galactic conflicts.
He could play the role of an outsider who disrupts the balance of power. His presence might force the Jedi and Sith to reevaluate their strategies as he has a completely different combat style.
In a fanfiction, perhaps Master Chief and Samus meet on a desolate planet. At first, they are cautious of each other, but as they realize they share a common goal of protecting the galaxy, they start to work together. They exchange knowledge about their respective worlds and enemies, leading to a deeper understanding and respect between them.
Another popular OC is a child prodigy who is a master of piloting. In the fanfiction, they team up with Master Chief and use their piloting skills to get them out of tough situations, like escaping a Covenant blockade. Their innocence combined with their amazing talent makes them a favorite among readers.
Another possibility is a crossover where Naruto is brought into the Halo universe. Naruto's chakra powers would be a very unique and powerful addition to the Halo setting. He could use his shadow clone jutsu to confuse the Covenant enemies. And perhaps Master Chief and Naruto could have a friendly sparring match to learn from each other's fighting styles.
One popular theme is crossovers. Writers like to imagine how the characters from RWBY would interact with Master Chief in different scenarios. It could be a battle scenario where they fight together against a common enemy, or a more peaceful encounter where they exchange knowledge or technology.
You can try fanfiction websites like Archive of Our Own (AO3) or FanFiction.net. These platforms usually have a wide variety of fanfictions, including those related to RWBY and Halo Master Chief. Just use the search function on the site and type in relevant keywords to find what you're looking for.
One interesting story could be about an Original Character (OC) joining Master Chief on a mission to save a colony. The OC might bring unique skills, like being a tech - genius who can hack into Covenant systems faster than Chief. This adds a new dynamic to their partnership.
One interesting Halo Master Chief lemon fanfiction might involve him in a unique adventure on a new alien planet. In this story, his skills are put to the test in a different environment, and there could be new characters that he teams up with. However, it's important to note that fanfiction can vary greatly in quality and adherence to the original Halo lore.