Hayato Gokudera is quite popular. In an alternate universe, he might be a lone samurai in a feudal Japan - like setting, or a tech - genius hacker in a cyberpunk world. Then there's Yamamoto. He could be a star athlete in a world where sports are the main focus instead of Mafia activities. His natural athleticism and positive attitude would make him a great character to develop in such a setting. Also, Hibari is often chosen. He could be the strict headmaster of a strict academy in an alternate educational - themed universe.
Among the female characters, Kyoko Sasagawa is popular. In an alternate universe, she could be a strong female knight in a medieval - like world, or a famous singer in a modern - day alternate universe with a focus on the entertainment industry. Haru Miura is also a good choice. Maybe she's a brilliant scientist in a world that values knowledge and discovery. And Chrome Dokuro could be a powerful witch in a magical alternate universe, with her powers being more developed and her character having a more central role.
Tsuna is often a popular choice. His growth and development throughout the original 'khr' series make him an interesting character to explore in a fanfic, especially when it comes to matters of love. He could fall in love with a new character or have a deeper relationship with an existing one.
Rey is often a popular character in Star Wars alternate universe fanfic. Writers like to explore different paths for her, such as her training under different Jedi masters or her relationship with other characters in new ways. Kylo Ren is also popular. Fanfic authors might write about his redemption in more complex scenarios than in the official story. And of course, Darth Vader. There are always fanfics that imagine what would have happened if he had survived and changed his ways, or if he had different relationships with other Sith or Jedi in the alternate universe.
Naruto himself is often reimagined. Writers like to explore different versions of him, such as a Naruto with a darker personality. Sasuke is also popular. In some AUs, he could be a more carefree character. And Kakashi is another one. Maybe a Kakashi who didn't have to endure so much trauma at a young age.
Scully is also highly popular. Her scientific mind and her relationship with Mulder, whether it's changed or intensified in the alternate universe, are always interesting aspects for fans to write about. Sometimes she might be even more of a skeptic or more open - minded depending on the fanfic's concept.
Well, in many Percy Jackson alternate universe fanfic, Leo Valdez is quite popular. People love to write about his inventions in different scenarios. Maybe he creates a super - powerful weapon that changes the balance of power between the demigods and the monsters. Grover also has his fans in these fics. He could be in a universe where he's the most powerful satyr ever and has to use his nature - related powers to save the world. And of course, Clarisse La Rue can be really interesting in alternate universes, like a Clarisse who teams up with her former enemies to fight a greater threat.
Severus Snape is a fan favorite in alternate universe stories. People are interested in seeing his character developed further, perhaps in a world where he didn't have such a complex relationship with Lily Potter. Harry Potter himself is, of course, a popular choice. Fanfic writers might create scenarios where Harry discovers his magic much earlier or has different adventures outside of Hogwarts that change his character development.
He - Man is obviously one of the most popular. He's the main hero, so many fanfictions revolve around his adventures, his battles against Skeletor, and his growth as a character. Skeletor is also very popular. His evil nature and his constant scheming make for great plotlines. People like to write about his attempts to take over Castle Grayskull and his interactions with his minions.
Sasuke is often very popular in Naruto AU fanfiction. His complex personality and powerful abilities make him a great character to reimagine in different universes. Naruto himself is also a common focus, as writers like to explore different versions of him.
In Avengers alternate universe fanfiction, Steve Rogers is quite popular. He represents the old - fashioned values and strong leadership, which can be a great contrast or a source of conflict in different universes. Thor is also well - liked. Imagining him in different settings, like a more modern or a more magical alternate universe, is really fascinating. Natasha Romanoff is popular too. Her skills as a spy and her complex past can be the basis for many engaging stories in alternate universes.
Hermione Granger is extremely popular. Writers often like to explore her intelligence further, perhaps in a scenario where she discovers a new branch of magic through her extensive research. Her relationship with Ron or Harry can also be delved into more deeply in fanfiction.