Obviously, Danny Phantom and Dan Phantom are the main characters. Danny is the original form, a heroic character, and Dan is his more evil and powerful transformation.
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.
Well, in some fanfictions, there are concepts like redemption arcs for Dan Phantom. It's fascinating to see how writers try to redeem such an evil character. Also, the idea of Danny using Dan's power for good in some unique situations. For example, there could be a story where Danny has to borrow Dan's strength temporarily to defeat a powerful ghost that he couldn't handle on his own.
Well, they might share some physical characteristics. Maybe in the fanfiction, Dan has the same white hair or green eyes as Danny Phantom. Also, their powers could be depicted in a similar way, like the ability to go intangible or fly.
One interesting plot twist could be that Danny's friends initially don't recognize him as Dan Phantom and try to befriend him, not realizing the danger. Another could be that Dan Phantom has some hidden memories of his time as Danny that start to resurface at crucial moments, changing his evil intentions.
Obviously, Danny Phantom is the main character as it's about his transformation into Dan. His friends like Sam and Tucker would also be important characters. They would likely play a role in trying to either stop the transformation or help Danny deal with the consequences. And of course, his ghostly foes might also be involved, as they could either take advantage of his situation or be affected by the power shift if he becomes Dan.
They could have the same basic build. Danny Phantom is usually shown as a teenage boy with a certain physique, and Dan in the fanfiction might be described in a similar way.
One possible plotline could be Danny's internal struggle as he starts to transform into Dan. Maybe he battles with the emerging dark thoughts and tries to resist the full transformation. Another could be how his friends and family react to the changes in him. They might initially not recognize the signs and then be horrified as he gets closer to becoming Dan.
Maddie is often depicted as a significant character. She might be a family member or someone closely involved with the main characters. But鍏蜂綋鐨勫叧绯 depends on the specific fanfiction.
Because Danny is the origin of Dan. He has a direct connection to the whole concept of Dan in the fanfiction. His actions and choices in the main story are what lead to the existence of Dan in the alternate or future scenarios.