Definitely Danny and Percy are the most prominent. However, in some more creative fanfictions, characters like Jazz from Danny Phantom might be included. She could offer a different perspective as Danny's sister, perhaps trying to understand the Percy Jackson world from a more scientific or psychological angle. And from Percy Jackson, Nico di Angelo could be a great addition. His powers over the dead could have some really interesting interactions with the ghosts in Danny Phantom. But still, Danny and Percy are the ones that draw the most attention as they are the face of their franchises and the ones that most readers want to see in these crossovers.
Percy himself is really popular. After all, the series is named after him. Fanfiction writers often like to put him in new and unexpected situations. Another popular character is Annabeth. Her intelligence and strategic mind make her a great addition to any new story line. Nico di Angelo is also quite popular as his dark and brooding nature offers a lot of potential for character development in drop - in fanfiction.
Jason Grace is a character that features a lot in fanfiction. His leadership skills and his connection to the Roman side of the demigod world are interesting aspects to write about. Fanfiction writers may explore his relationship with Percy, especially how they combine their different leadership styles when facing challenges together, and his struggle to adapt to the Greek demigod world after being brought to Camp Half - Blood.
In Danny Phantom, Danny himself is often a popular choice. His cool powers and heroic nature make him a great addition to any crossover. In My Little Pony, Twilight Sparkle is a common character in fanfiction. She's intelligent and powerful, so she could interact well with Danny.
Some fanfictions might explore a storyline where the characters from Danny Phantom and Percy Jackson are swapped in their respective worlds. Percy in Amity Park having to deal with ghosts and Danny in the demigod world having to face the challenges there. This could lead to some really fun and unique character interactions. Another idea could be a crossover of their friends and allies. So, Tucker and Annabeth working together to come up with a plan, or Sam and Grover on an adventure to find a magical item that can help Danny and Percy in their fight against the combined threats of their two worlds.
Obviously, Danny and Dan themselves are very popular. Danny as the main hero and Dan as his dark and complex counterpart are central to many stories. Jazz, Danny's sister, is also popular as she can provide a different perspective and often gets involved in Danny's ghost - fighting adventures in fanfiction.
Annabeth is also a very popular choice. Her intelligence and her relationship with Percy are often explored in fanfics. Writers might create scenarios where she uses her smarts to solve complex problems or where her relationship with Percy is put to the test in new and interesting ways.
Danny himself is often very popular. His dual identity as a normal teen and a powerful ghost makes for interesting stories. Also, Robin, with his acrobatic skills and detective mind, is a favorite. Writers like to explore how he would react to the supernatural elements in Danny's world.
Well, obviously Danny and Vlad are very popular. Danny is the main character in the show and in fanfiction, his adventures and growth are always a focus. His ability to balance his human life and his ghost - fighting duties makes him a complex and interesting character to write about.
Danny himself is often a very popular character. After all, he's the main character of the original series, so in fanfiction, his adventures are usually central. Sam and Tucker are also quite popular as they are Danny's closest friends. Their relationships with Danny and how they support him in different situations are often explored in fanfiction.
Sam and Tucker are also quite popular. In the multiverse fanfiction, they can have different roles. Maybe in one story, Sam has some hidden ghost powers of her own and becomes a key player in a multiverse adventure. Tucker could be a tech - genius in one universe and a powerful magician in another, adding new dimensions to their characters.