I think Ruby and a young, adventurous Pilot would make a great pairing. Ruby's enthusiasm and eagerness to learn new things would mesh well with a Pilot's daredevil nature. They could exchange stories about their respective worlds while fighting side by side.
Zero and Ruby would be a likely pairing. Zero is a powerful and skilled fighter, and Ruby has a lot of potential and a unique weapon. They could learn from each other's combat styles. Ruby could learn about Zero's more serious and battle - hardened approach, while Zero could be inspired by Ruby's enthusiasm and creativity in fighting.
Kirby and Yang could also make an interesting pairing. Yang is strong and brash, while Kirby is small but mighty. Their personalities contrast but could also complement each other well. Yang could provide the brute force while Kirby could use his unique powers to support her in battles, like when she's facing a particularly tough Grimm.
Ruby could also be a great candidate. Her natural leadership skills and her ability to quickly adapt to new situations would serve her well. Plus, her speed and agility could make her an excellent Pilot. She might even come up with new strategies for using the Titans in combat, inspired by her own experiences in RWBY.
The Doom Slayer and Ruby would be an interesting pairing. Ruby is young and full of energy and hope, while the Doom Slayer is a silent, stoic force of destruction against evil. Their interactions could be really cool, like Ruby trying to understand the Doom Slayer's lack of words but seeing his determination and being inspired by it. And the Doom Slayer might see Ruby's potential and unwavering spirit in the face of danger as something similar to his own.
Ruby and Noel would be a great pairing. Ruby is young, energetic, and has a strong sense of justice. Noel is also a very determined and kind - hearted character. They could bond over their shared values and also learn from each other's combat styles. Ruby could show Noel some of her acrobatic moves with Crescent Rose, while Noel could teach Ruby some of the finer points of her swordsmanship.
Ruby and Frisk would be a really interesting pairing. Ruby is full of energy and determination, and Frisk has that unwavering kindness. They could learn a lot from each other, especially in terms of how they approach difficult situations and make decisions.
I think Ruby and the Dragonborn would be an interesting pairing. Ruby is young and full of energy, and the Dragonborn has a lot of power and experience. Ruby could learn a lot about different forms of combat from the Dragonborn, and the Dragonborn could be inspired by Ruby's positive attitude.
I think Uryu and Weiss could be a fascinating pairing. Uryu is the Quincy with his pride in his heritage, and Weiss is the Schnee heiress with her own sense of family pride. They could have some intense debates about their families and legacies. At the same time, they could learn from each other's combat styles. Uryu could show Weiss how to be more adaptable in battle, while Weiss could teach Uryu about the importance of elegance in combat.
I think Mercy and Ruby would make an interesting pairing. Mercy is a healer in Overwatch and Ruby is the leader of Team RWBY. Ruby could learn about Mercy's advanced medical technology and how she uses it in combat. Meanwhile, Mercy could be inspired by Ruby's determination and leadership. Another great pairing could be Winston and Yang. Winston is a brilliant scientist and a powerful fighter as a gorilla. Yang is a brawler with a lot of strength. They could have some epic sparring sessions and also exchange knowledge about strength - based fighting and scientific inventions.
Ruby and Yu Narukami. Ruby is young and full of energy, always eager to fight for what's right. Yu is a calm and collected leader. Their different personalities would make for an interesting dynamic. Ruby could learn from Yu's more methodical approach to problem - solving, while Yu could be inspired by Ruby's unwavering determination.