Well, there's 'RWBY and the Space Marine Encounter'. This fanfiction dives deep into the initial shock and then the slow - building cooperation between the RWBY team and the Space Marines. It explores how their different powers and abilities can complement each other in battles against powerful foes that threaten both their worlds.
Another good one is 'Space Marines: Redemption'. This fanfiction follows a fallen Space Marine who tries to find redemption. The story has a lot of moral dilemmas and the writer does a great job of exploring the psyche of a Space Marine who has strayed from the path of the Emperor. It's a very character - driven story that keeps you hooked from start to finish.
In many RWBY Space Marine fanfictions, they merge the two universes by having a portal or some sort of interdimensional rift. This allows the Space Marines to end up in the RWBY world. For example, in 'The Astartes of Remnant', a warp - like portal sucks in a group of Space Marines and drops them right into the middle of Vale.
One great 'tails and marine' fanfiction could be 'The Adventures of Tails in the Marine World'. It has an interesting plot where Tails discovers a hidden underwater civilization. He uses his mechanical skills to help the marine creatures there, which makes for an exciting read.
One interesting RWBY Bayonetta fanfiction is 'The Crossover of Hunters and Umbra Witches'. It combines the unique combat styles of both universes really well. The characters from RWBY and Bayonetta interact in a way that feels natural and the plot is full of action.
One great RWBY Guyver fanfiction is 'The Guyver in Remnant'. It combines the unique powers of the Guyver units with the RWBY universe in an exciting way. The main character, a Guyver user, teams up with the RWBY girls to face new threats. Another interesting one is 'Guyver: A New Force in Vale'. It explores how the arrival of the Guyver technology could change the power dynamics in Vale.
One great RWBY and Digimon fanfiction is 'Digimon in Remnant'. It combines the unique worlds really well. The characters from RWBY interact with Digimon in a believable way.
I really liked 'Neo's Team - Up'. In this fanfic, Neo teams up with some unexpected characters from another series. The way the author weaves the two universes together is really engaging. They handle Neo's silent yet expressive nature very well in the interactions.
One great RWBY x Legend of Zelda fanfiction is 'The Huntress in Hyrule'. It combines the action - packed world of RWBY with the magical realm of Zelda. The main character from RWBY is transported to Hyrule and has to face the challenges there while also using her unique skills. Another interesting one is 'Link and the Huntsmen'. It focuses on a crossover adventure where Link teams up with the RWBY characters to defeat a common enemy that threatens both their worlds.
One great RWBY and Captain Marvel fanfiction is 'A Meeting of Heroes'. In this story, the characters from RWBY's Remnant world somehow cross paths with Captain Marvel. It has really exciting action scenes where Ruby's scythe skills are combined with Captain Marvel's photon blasts. The story does a good job of balancing the different power levels and personalities of the characters.
One interesting 'RWBY Barefoot Ruby Fanfiction' could be those that focus on Ruby's adventures in a more vulnerable state, like when she's barefoot. For example, some fanfictions might explore how she has to adapt her combat style without proper footwear. It can add an interesting layer to her character development.