Sheldon himself is often a popular choice. Writers like to explore what would happen if he was reborn with some changes, like being more socially adept from the start. It adds a new dimension to his character.
Missy is also a common one. People might have her reborn with a different set of skills or knowledge. Maybe she becomes a genius in a different field than Sheldon and they end up competing in a friendly way. This can lead to some great sibling rivalry storylines.
Some fanfictions feature Penny being reborn in the Young Sheldon universe. It's interesting because she has to deal with the much younger versions of the characters she knew in 'The Big Bang Theory'. Her modern - day knowledge and attitude can cause quite a stir in the more innocent and old - fashioned world of Young Sheldon.
One idea could be a character from the future getting reborn in the Young Sheldon universe and using their modern knowledge to help Sheldon with his scientific experiments in a unique way. For example, they might introduce a new concept that wasn't known in that time period but accelerates his research.
Well, in addition to the main characters like Sheldon, Georgie is a popular character to include in Young Sheldon fanfiction. He represents a different kind of kid, more interested in sports and girls rather than science. His relationship with Sheldon, which is a mix of teasing and protecting, can be really fun to write about. Also, Dr. Sturgis, Sheldon's mentor, is often in fanfictions. His guidance and his own quirks can be explored further in the fan - created stories.
Harry Potter himself is often a popular reborn character. Writers like to explore what would happen if he had a second chance at life and could change things. It allows for a lot of creative interpretations of his character growth and how he would handle the challenges differently.
Apollo is often a favorite. He's the god of music, poetry, and prophecy. Reborn as Apollo, the character could explore the world of art in the Greek setting and also use their prophetic powers in interesting ways. Also, Poseidon is popular. With his control over the seas, there are many nautical adventures and power struggles that can be written about.
Goku is often a popular choice. Since he is the main protagonist of the Dragon Ball series, imagining him being reborn with different powers or in a different situation can be really exciting. For example, being reborn as a half - human, half - Namekian with the ability to use Namekian techniques along with his Saiyan powers.
In this type of fanfiction, the main character, the reborn dinosaur, is of course a popular one. But sometimes, there are other characters like a group of friendly herbivore dinosaurs that the reborn dinosaur befriends. They could be characters like a triceratops or a stegosaurus. And then there could be the antagonist, perhaps a large and aggressive tyrannosaurus rex that constantly hunts the reborn dinosaur or tries to drive it out of its territory.
Batman himself is obviously a very popular character in batman reborn fanfiction. Writers often explore different aspects of his personality, like his internal struggles with his dual identity.
Gon is a popular choice. He has a strong sense of justice and determination. Reborn as Gon, one could explore his journey again but with a different approach, like using knowledge from a previous life to avoid some of the hardships he faced. His connection to nen and his growth throughout the series make him an appealing character to be reborn as.
Nero is also a popular character to be paired with the reborn as Vergil. Given Nero's connection to Vergil in the original story, in fanfiction, their interactions can range from mentorship - where Vergil helps Nero master his powers, to more adversarial relationships if the reborn Vergil has different motives.
Naruto himself is often a central and very popular character in these fanfictions. Since it's about his rebirth, readers are interested in seeing how his character evolves differently.