Ruby would be really interesting. Her optimism and determination in RWBY could be a great contrast to the often dark and foreboding nature of the Dark Tower universe. She could inspire the characters there with her can - do attitude and also learn a lot from the more cynical or world - weary characters in the Dark Tower world.
The character of Roland from the Dark Tower series could be an interesting focus if incorporated into RWBY Dark Tower fanfiction. His quest for the Dark Tower is so central to his character. If he were to interact with the RWBY team, he could teach them about perseverance in the face of seemingly insurmountable odds. He might also be impressed by their unique abilities and how they work together as a team.
Mercury from RWBY could be an interesting character to focus on. He has a rather morally ambiguous nature already. In a Darkwatch fanfiction, he could be tempted by the power of the Darkwatch's enemies, like the vampires or demons. His prosthetic legs could also be given some kind of dark upgrade, and we could see him struggle between his own self - interest and the greater good in this new and dangerous setting.
Ruby could be really interesting. Her naivete and pure - hearted nature would contrast with the often - cynical and war - torn world of the Clone Wars. She could inspire the clones and Jedi with her unwavering belief in doing good, and her scythe - wielding skills would be a unique addition to the battles.
Ruby would be really interesting. Her energetic and optimistic nature would contrast greatly with the often dark and power - hungry characters in the Overlord world. She could inspire some of the downtrodden minions with her belief in the good of people. Also, her scythe skills and speed would be a unique addition to the battles in the Overlord universe.
Ruby. She has that innocent and curious nature which would make her reactions in the SAO world really interesting. She could be fascinated by the virtual world and its different rules, and her positive attitude might be a source of hope for the other characters. Also, her scythe - using skills could be adapted in the SAO combat scenarios in unique ways.
Yang from RWBY would be another interesting choice. Her fiery personality and powerful punches could bring a different kind of energy to the Halo Wars universe. She might get into some interesting battles with the Covenant, using her brute strength and her Semblance of absorbing damage to become even stronger in combat.
I think Blake would also be a great focus. Her stealth and agility would translate well in the Monster Hunter world. Plus, her cat - like Faunus traits could give her an edge in certain situations, like tracking or sneaking up on monsters.
I think Ruby would be a great choice. Her innocence and determination in RWBY could be an interesting contrast to the often more battle - hardened and power - hungry characters in Dragon Ball. She could learn a lot from them about power and also teach them about the importance of friendship and teamwork in a different way.
Ruby would be really interesting. Her innocent and positive attitude would contrast greatly with the dark and desolate Fallout world. She'd be like a ray of hope in the wasteland. Her scythe - fighting skills would also be unique and useful against the various threats in Fallout. She might try to befriend some of the mutants or ghouls, seeing them not as just monsters but as living beings who need help.
Ruby from RWBY could be a great focus. Imagine if she were to encounter the psychic abilities from Mob Psycho 100. She could learn about a different kind of power and how to incorporate it into her fighting style. Her positive and determined attitude would also make for some interesting interactions with the more reserved or complex characters from Mob Psycho 100.
Sinister characters like Adam Taurus from RWBY could also be interesting in a Bloodborne crossover. His already dark and violent nature could be enhanced in the Bloodborne setting. He could form alliances with some of the more sinister forces in Bloodborne, or perhaps he becomes a sort of anti - hero, fighting against the greater evils in the Bloodborne world while still being a morally ambiguous figure.