Finn from Glee and Iris from the Flash might be another popular combination. Finn is the football - star - turned - singer, and Iris is a strong journalist. Their different worlds colliding could lead to a story full of love, friendship, and adventure as they support each other in their respective goals.
Kurt from Glee and Cisco from the Flash could also be a popular pairing. Kurt is known for his fashion sense and his sassy personality, and Cisco is the tech - genius of the Flash team. They could bond over their creativity, with Kurt helping Cisco with his style and Cisco introducing Kurt to some cool tech gadgets.
Finn from Glee and Harry Potter himself could be paired in fanfiction. Finn has his leadership qualities in the Glee club, much like Harry has in the wizarding world. They could bond over their responsibilities and face challenges together, whether it's fighting off the Death Eaters or dealing with high - school - like rivalries in the case of Finn in the Glee world.
Octavia is also a character who gets paired a lot in crossovers. If there's a crossover with a show like 'Once Upon a Time', she could be paired with a character like Regina. The contrast between Octavia's warrior - like nature and Regina's more complex, magical personality would make for a great story. And of course, Murphy is often paired in crossovers. He could be paired with a character from a show like 'Falling Skies', and their shared experiences of being outsiders in their respective worlds could lead to an interesting relationship.
One popular character paired with Ichigo is Naruto. Their different power sets and personalities make for an interesting combination. Naruto's positive and determined attitude could contrast with Ichigo's sometimes brooding nature. Another is Luffy from 'One Piece'. Luffy's carefree and adventurous spirit next to Ichigo's more serious approach to protecting his friends can create some great stories.
Definitely Naruto and Flash (Barry Allen) themselves. They are the main characters of their respective series, so it's natural that they are at the center of most crossovers. But also, characters like Sasuke from Naruto can be popular. His cool and brooding nature contrasts well with the more upbeat Flash characters. And on The Flash's side, characters like Iris West could also be interesting in the crossover as they could bring a different dynamic to the story.
Obviously, The Flash and Arrow themselves are must - includes. Their dynamic and different power sets make for great interactions. Also, Cisco Ramon from the Flash side is popular as he can bring in his tech - wizardry to help in the crossover.
Madara is quite commonly paired with Hashirama in crossover fanfiction. Their complex relationship in the original Naruto series makes for interesting scenarios when they are placed in different crossover settings. They could be forced to work together against a new threat or their rivalry could take on new dimensions in a different world.
Gwen Tennyson is often paired with Ben 10000. Since they are related in the original series, it's interesting to see how their relationship might be different in a crossover scenario. Maybe they have to work together to save the universe in a more complex way than before.
Nightwing is often paired with Batgirl. They have a history together, and in crossover fanfiction, they can have some great team - up moments. Whether it's fighting crime in Blüdhaven or Gotham, their combined skills are quite formidable. Also, Harley Quinn is a popular character to pair with Batgirl. Their interactions can range from comical to intense, as they have very different personalities but can find common ground in certain situations.
Goku is often paired with Bardock in crossover fanfiction. Since they are father - son, it's natural to explore their relationship in different crossovers. They might team up against a powerful enemy from another universe or have heart - to - heart conversations about their Saiyan heritage.
I think Barry Allen and Rachel Berry would make an interesting pairing. Barry is all about saving the day and being a hero, while Rachel is very ambitious and determined in her singing career. They could learn from each other's perseverance. For instance, Barry could teach Rachel about the importance of quick thinking in difficult situations, and Rachel could inspire Barry with her unwavering dedication to her art.