Frisk and Dave Strider would be an interesting pairing. Frisk is all about kindness and determination in Undertale, while Dave is this cool, sarcastic guy from Homestuck. Their different personalities could lead to some really fun interactions, like Dave trying to be all cool while Frisk just goes about their business of being kind to everyone.
Papyrus and Tavros would be an exciting pairing. Papyrus is always full of enthusiasm and wants to be part of the Royal Guard in Undertale. Tavros is a bit more timid in Homestuck. Papyrus could try to give Tavros some confidence lessons, and Tavros could show Papyrus some of his unique abilities from Homestuck. It would be a great dynamic of an over - confident and an under - confident character.
I think John Egbert from Homestuck and Bob the Tomato from Veggietales would be really interesting. John is this really optimistic and kind of goofy character, and Bob is always so level - headed and full of wisdom. Their interactions could be really fun, like John trying to understand Bob's simple but profound view on life, and Bob trying to keep up with John's wild ideas.
Russia from Hetalia and Kanaya from Homestuck could be a really unique pairing. Russia has his own mysterious and somewhat intimidating aura, and Kanaya is very poised and has her own set of skills, especially when it comes to fashion and fighting. Their interactions could be quite interesting, like Russia showing Kanaya some of his traditional Russian crafts and Kanaya showing Russia how to make some really cool Homestuck - inspired outfits. Additionally, China from Hetalia and Jade from Homestuck could be a great pair. China with his long history and Jade with her connection to nature and her rather innocent yet powerful nature could create some really engaging storylines.
Naruto and Frisk would be really interesting. Naruto is all about never giving up and has a strong sense of justice, while Frisk is determined in their own way, always choosing the path of peace and kindness in Undertale. Their combined determination could lead to some great adventures and they could learn a lot from each other's ways of dealing with challenges.
Alphys and Iron Man. Alphys is a scientist in Undertale who is a bit of a klutz but also brilliant. Iron Man is a genius inventor in Marvel. They could collaborate on some crazy technological inventions. Alphys could learn a lot from Iron Man about presenting herself more confidently, and Iron Man could be intrigued by Alphys' unique approach to science that comes from the Undertale world.
I think Leonardo and Papyrus would make an interesting pairing. Leonardo's leadership and discipline could contrast with Papyrus' more naive and enthusiastic nature. They could learn from each other, like Leonardo teaching Papyrus some ninja moves, and Papyrus showing Leonardo how to have more fun. Another great pairing could be Donatello and Alphys. They are both the 'tech - smart' characters in their respective universes. They could collaborate on some crazy inventions that combine Undertale technology and Turtle - made gadgets.
I think Freddy Fazbear and Toriel would make an interesting pairing. Freddy is this big, imposing animatronic, while Toriel is a motherly figure. Their interactions could be really cool, like Toriel trying to understand what Freddy is and Freddy being a bit confused by Toriel's kindness.
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.
Grunkle Stan and Toriel could be an interesting pairing. Grunkle Stan is a bit of a con artist but has a good heart deep down. Toriel is a motherly figure. They could have some great interactions where Toriel tries to get Stan to be more honest and kind, while Stan might try to find some business opportunities in the Undertale world. It would be a clash of personalities but also a chance for growth for both characters.
Another interesting pairing would be Ron and Papyrus. Ron is known for his loyalty and his love for food, and Papyrus is this enthusiastic skeleton who loves cooking and making friends. They could bond over food, with Ron introducing Papyrus to some wizarding world delicacies like Butterbeer and Pumpkin Pasties, and Papyrus showing Ron his 'Spaghetti Surprise'. Their friendship could also be a source of comic relief in a more serious crossover story.
Akira and Minato would be an interesting pairing. Akira, with his leadership skills as the leader of the Phantom Thieves, and Minato, the protagonist of Persona 3, could share their strategies in combat and dealing with the Metaverse. They both have different experiences with their respective groups, so they could learn a lot from each other.