Zim and Bender would be a really interesting interaction. Zim is this over - confident alien bent on world domination, while Bender is a self - centered, kleptomaniac robot. They could start off by trying to out - do each other in terms of causing chaos or stealing things. GIR and Fry could also be a fun pair. Fry's simple - mindedness would match well with GIR's random and silly behavior. They could get into all sorts of comical situations together, like accidentally starting a food fight in the Planet Express cafeteria.
Dib and Leela would have an interesting dynamic. Dib is always the outcast on Earth because of his obsession with Zim. Leela, as a strong - willed mutant in a world that often discriminates against her, can understand being an outsider. They could share their stories and then team up to stop Zim. Another interesting interaction would be between the Professor and Zim. The Professor is a brilliant but often scatter - brained scientist. Zim could be both intrigued and frustrated by the Professor's inventions, which might be a great source of conflict and comedy in the story.
One possible plot could be that Zim and Dib from 'Invader Zim' somehow end up in the 'Futurama' universe. Zim might see the advanced technology in Futurama as a new opportunity to take over a planet. He could mistake Planet Express for a major power center and try to infiltrate it. Dib, on the other hand, would be excited to explore this new world and might team up with Fry, Leela, and Bender to stop Zim's new evil plan.
I think Steven and Zim would be the most interesting pair. Steven's kind - hearted and positive nature contrasted with Zim's evil and self - centered personality would create a lot of comical and tense moments.
Ruby and Zim could be an interesting pairing. Ruby is young and full of energy and optimism, while Zim is completely delusional and self - centered. Their interactions would be full of misunderstandings and comical moments as Ruby tries to understand Zim's alien ways and Zim just sees Ruby as another obstacle in his plan to conquer Earth.
Gir could also be a great focus. His love for food and randomness could add a really fun element. Imagine Gir befriending the Powerpuff Girls and getting them into all sorts of silly adventures, while Zim is fuming in the background because Gir is not helping with his evil plans.
One of the most interesting interactions could be between Sasuke and Zoidberg. Sasuke is this brooding, powerful ninja, and Zoidberg is this clumsy, loveable lobster - doctor. Sasuke might be initially disgusted by Zoidberg's appearance but as he gets to know him, he realizes that Zoidberg has a good heart. Zoidberg, on the other hand, would be in awe of Sasuke's power. Also, Hinata and Amy could have a really sweet interaction. Hinata is shy and gentle, and Amy is confident and intelligent. They could exchange stories about their respective worlds and form a really nice friendship.
Definitely Joker and Makoto Yuki. Joker is the leader of the Phantom Thieves, very confident and strategic, while Makoto Yuki is a strong and silent type. Their leadership styles could clash or complement each other.
Definitely the interactions between the two versions of Leonardo. The 2012 Leo is more light - hearted in some ways compared to the very serious 2003 Leo. They could have some great moments of leadership clashes and then learning from each other. For example, the 2003 Leo could teach the 2012 Leo some of his more stoic leadership techniques.
I think the interaction between Joker (from Persona 5) and Yu (from Persona 4) would be really interesting. They are both leaders of their respective groups, so they could exchange leadership strategies and learn from each other. Also, Morgana and Teddie would be hilarious together. Morgana's serious yet sometimes clueless nature and Teddie's over - the - top and comical personality would create some great comedic moments.
Definitely Dib and Dipper. They are both curious and into the strange and supernatural. Dib with his alien - hunting skills and Dipper with his knowledge of the Gravity Falls mysteries would make a great pair.
Definitely Clark Kent and Dean Winchester. Dean has his tough - guy hunter persona, while Clark is the all - American good guy with superpowers. Their different approaches to protecting people would make for some great banter and clashes of ideology. Another interesting interaction would be between Sam Winchester and Lex Luthor. Sam's intelligence and his experience with the supernatural could put him at odds with Lex's brilliant but often morally - grey mind. And Castiel and Chloe Sullivan could also have an interesting dynamic. Castiel's otherworldly nature and Chloe's inquisitive journalist side would lead to some really unique conversations.