Harry Potter might also be a main character. Given his own experiences as the supposed 'chosen one', he could have mixed feelings about Draco taking on this role. He might be jealous at first, but then realizes that they need to work together to face a greater threat. Their relationship would be a key aspect of the story, evolving from rivalry to a sort of partnership.
Snape could be another important character. Snape has always had a complex relationship with Draco. If Draco is the chosen one, Snape might be in a difficult position. He has to balance his loyalty to Draco's family and his own sense of what is right for the wizarding world. His actions and decisions would greatly impact Draco's journey as the chosen one.
Hermione could be a main character. She might be the one who first suspects Draco's new role as the chosen one. Hermione's intelligence and inquisitive nature would lead her to notice the strange things happening around Draco. She could either be an ally or a skeptic, depending on how the story unfolds.
Another possible main character could be Snape. Given Snape's complex relationship with Draco in the original series, in this fanfiction, he could be either a mentor to Draco in his prodigious journey or have a more conflicted role as he tries to balance Draco's new status with the existing power structures in Hogwarts.
Another possibility is that a new original character could be the main character. This character could be a house - elf who is in charge of cleaning the bathrooms and has some interesting interactions with Draco while he's in the shower.
His father, Lucius Malfoy, might also be a main character. Lucius, who is always so concerned about appearances and family reputation, would be horrified by Draco's slobbishness. There could be a lot of conflict between them as Lucius tries to force Draco to be presentable again. And then there's Hermione Granger. Since she's always so neat and organized, she might be appalled by Draco's slobbish ways and get involved in some sort of rivalry or strange friendship with him because of it.
Hermione could be a main character. She might be the one who discovers Draco's situation and tries to help him out of pity or a sense of justice. Harry could also be involved, perhaps initially being suspicious of Draco's new state but then realizing it's not a trick.
Hermione could be a main character. Given her strong stance on equality, she might initially be suspicious of Draco but later come to understand his internal struggle as a half - blood. Their interactions could be filled with tension and, eventually, mutual understanding.
Harry Potter could be one of the main characters. Since he has a complex relationship with Draco, he might be intrigued by Draco's sleep - talking and try to use it to gain some understanding of Draco or even to tease him.
Hermione is a very popular choice. Her intelligence and strong will can create interesting dynamics with Draco. Harry could also be included, as his rivalry with Draco is well - known. And then there's Ginny. Her fiery personality can add a lot of spice to the story when interacting with Draco.
Harry Potter would surely be one of the key characters. His relationship with Draco, which has always been a mix of rivalry and grudging respect, could play a huge role. As Draco switches sides, Harry would be initially suspicious but then come to accept and work with him. Hermione Granger is also likely to be important. Her intelligence and strong moral compass could influence Draco further and she could be the one to first recognize his change of heart.
In this fanfiction, Gary could be an important character. Since he has always been in competition with Ash, he might have mixed feelings about Ash being the chosen one. Serena could also be a main character. She might be inspired by Ash's chosen - one journey and decide to follow him, offering her own skills and support. Professor Oak would likely be involved as well, guiding Ash with his vast knowledge of Pokémon.
One interesting plot could be Draco having to hide his 'chosen one' status from his Death Eater family. He might struggle with the conflicting loyalties, torn between his family's dark path and his newfound destiny as the chosen one. This could lead to some intense internal battles and secretive actions as he tries to figure out how to use his new role for good without getting caught by his family.