Hermione could be a great main character. She's smart and curious, so if she ended up in the Wings of Fire world, she would be eager to learn about the dragons and their society. She could use her knowledge of magic from Harry Potter to interact with the new world and might even try to find a way to combine the two magics.
A dragon from Wings of Fire like Clay could also be the main character. If he found his way to the Harry Potter universe, he could be fascinated by the different kinds of magic there. He might try to adapt to the human - dominated world of Hogwarts while also trying to keep his dragon identity a secret, which would lead to many interesting situations and challenges.
There could be a magical creature that takes on a human - like form and has black angel wings. This creature could be a guardian of some sort, maybe of an important magical artifact. It might initially be seen as a threat but is actually there to protect the wizarding world. When Harry discovers this creature, they form an unlikely bond, and the black angel wings become a symbol of their unique relationship.
It could be a Gryffindor student. Gryffindors are known for their bravery, and sometimes that can lead to them taking risks that are like playing with fire. Maybe a young Gryffindor who is overconfident and gets into trouble by trying to prove themselves.
It could be a power - hungry dragon from a minor tribe that feels overlooked. This dragon might see Peacemaker as an obstacle to their own plans of taking over and ruling all the tribes. They would use devious means, like creating false alliances and then betraying them, all while trying to get rid of Peacemaker. They might also try to turn Peacemaker's friends against him by using their insecurities and secrets. In this way, they would be a formidable antagonist in the fanfiction.
Hermione could also be a main character in this fanfiction. Her intelligence combined with the new element of wings could lead to some really interesting plot developments. She might study the magic behind the wings and find ways to use it to help her friends.
It could be another character who has a deep understanding of magical creatures, like Hagrid. Since the character with wings is related to Charlie in some way, and Charlie is into dragons, Hagrid's knowledge of all kinds of magical creatures might make him a suitable mate. He could help take care of the winged character and understand their unique needs.
A powerful dark wizard who has a grudge against those with fire - related magic could be the main antagonist. He might see Harry's newfound 'Son of Fire' powers as a threat to his own plans for domination.
For the Wings of Fire side, it could be Clay. His strong and kind - hearted nature would make him an interesting character to be thrust into the SAW world. He would try to protect the others and use his earth - related dragon abilities to his advantage. From the SAW side, maybe Jigsaw could be a main character. His complex and twisted motives would create a lot of tension when interacting with the Wings of Fire characters.
There could be many amateur authors out there who might write such a fanfiction. It could be a young, creative Harry Potter fan who loves to imagine new and exciting adventures for the characters. They might be inspired by their love for the series and the idea of giving Harry a new and unique ability like growing wings.
It could be a powerful dark wizard who has infiltrated the Ministry of Magic and manipulated the Goblet of Fire. They might want Harry out of the way to further their own dark plans.
Maybe it's a new character, a powerful dark wizard who has a vendetta against Dumbledore. By forcing Harry into the tournament, they hope to draw Dumbledore out and make him vulnerable. This new antagonist could have some dark magic at their disposal that allows them to control the Goblet's selection process.