Steve and Ron would be a really fun pairing. Ron could introduce Steve to the wizarding world's food and traditions, and Steve could show Ron how to be a bit cooler and more confident in social situations. Also, Joyce and Molly Weasley would be an interesting pair. They are both strong mother figures, and it would be fascinating to see them bond over protecting their kids and dealing with the strange situations in both universes.
Definitely Harry and Eleven. Harry has his own special powers in the wizarding world, being able to speak Parseltongue and having the power of love that saved him from Voldemort. Eleven has her telekinesis and other abilities. They could learn from each other. Harry could teach Eleven about the different types of magic, and Eleven could show Harry how to use her powers in a more creative way. Another interesting pairing would be Hermione and Dustin. They're both super smart. Hermione could introduce Dustin to the vast library of Hogwarts and all the knowledge it holds, while Dustin could share his knowledge of science and technology with Hermione, and they could come up with some really cool ideas that combine magic and science.
I think Eleven and Bill would make an interesting pairing. Eleven has her telekinetic powers and has faced otherworldly threats in the Upside Down. Bill is the leader of the Losers' Club and is very brave. Together, they could lead their respective groups in a fight against the combined threats of the Demogorgon and Pennywise.
Another great pairing could be Richie and Dustin. They both have a sense of humor that they use to cope with difficult situations. Richie's quick - witted remarks and Dustin's scientific knowledge could create some really interesting interactions. They could be the ones who try to figure out the scientific or otherworldly aspects of the crossover, like how the powers in Stranger Things relate to the strange entity that is It. Plus, their banter would be really entertaining.
Betty and Eleven would make an interesting pair. Betty has her own dark secrets and determination in Riverdale, and Eleven has her powers and a past full of mystery in Stranger Things. They could help each other out in different ways, like Betty helping Eleven understand normal human relationships, and Eleven using her powers to protect Betty when she's in danger.
Definitely Eleven and Captain America. Steve's leadership and moral compass combined with Eleven's raw power would be a great combination. They could inspire each other in different ways.
Harry and Elsa would be a very interesting pairing. Harry, with his experience in facing dark magic, could offer Elsa a new perspective on her powers which she has always seen as a curse. And Elsa, with her ice powers, could show Harry a different kind of magic that he's not used to in the wizarding world. Another interesting pairing would be Ron and Kristoff. They both have a simple - minded charm and could get into all sorts of funny situations together, like getting lost in the Forbidden Forest or on the mountains in Arendelle. Also, Hermione and Anna would be great. Hermione's intelligence and Anna's determination would make them a formidable duo as they try to solve problems in both their worlds.
I think Harry Potter and Nick Burkhardt would be an interesting pairing. Harry has his experience with fighting dark magic and Nick has his knowledge of the Wesen world. They could learn a lot from each other. Harry could teach Nick about some of the more complex spells, while Nick could introduce Harry to the different types of Wesen and how to deal with them.
I think Luna Lovegood and Prompto would make a really fun pairing. Luna has her unique and somewhat otherworldly view of things, and Prompto is the cheerful and energetic one in the FFXV group. They could have some really interesting conversations about the strange creatures in both their worlds. Also, Severus Snape and Gladio could be an unexpected but fascinating pairing. Snape's dark and brooding nature contrasted with Gladio's tough and protective side.
Harry Potter himself could also be a very powerful character in the merged universe. He has his own magical skills and the experience of fighting dark wizards. He could teach the Stranger Things characters about the wizarding world and use his magic to protect them from the Upside Down threats. Also, his connection to Voldemort might give him some unique insights into defeating any dark forces that come from the merging of the two universes.
Hermione Granger and Rukia Kuchiki could make a great pairing. Hermione is extremely intelligent and well - versed in magic theory. Rukia, on the other hand, has a deep understanding of the spiritual world. They could collaborate on researching a strange phenomenon that is occurring between the two worlds, like a merging of certain spells and Soul Reaper techniques. Their different personalities would also create some interesting interactions, with Hermione being more outspoken and Rukia more reserved.