There could also be other characters from either Stiles' world or the Winchesters' world that make appearances. For example, in Stiles' world, there might be his friends like Scott who could be mentioned or even play a small part in the story. And from the Winchesters' side, characters like Castiel could potentially show up and interact with Stiles in some really interesting ways.
One interesting plotline could be Stiles teaming up with the Winchesters to hunt a particularly elusive and dangerous supernatural creature. Maybe it's a new type of werewolf that has powers they've never encountered before.
The main characters are Stiles and the Cullens. Stiles is known for his ability to adapt in strange situations. When he meets the Cullens, their interactions will be centered around how they deal with each other's differences. The Cullens' vampiric abilities and Stiles' human (or whatever he is in his original context) nature will play a big part in their relationships in the fanfiction.
Stiles is the key character here. He's the one through whose perspective we usually experience the story. In the pack, Scott is a must - he's the werewolf who has a long - standing friendship with Stiles. Derek, with his alpha - like presence, also plays a major role. Additionally, characters like Allison, who has her own arc related to the supernatural world, could be part of the main cast as well. They all interact with Stiles in different ways when he meets the pack.
At the beginning, there could be a lot of misunderstandings. The Winchesters might not understand Hermione's magic, thinking it's some kind of hocus - pocus. But as they face challenges together, like fighting a powerful demon that's immune to their usual methods but vulnerable to Hermione's spells, they would bond. Their relationships would develop into a deep friendship where they rely on each other, with Hermione becoming an important part of their hunting team, and the Winchesters being her allies in the non - wizarding world.
Obviously, Stiles and members of the Hale family are the main characters. Stiles, with his quick thinking and sarcastic humor. And the Hale family members, like Derek Hale, who is often portrayed as brooding and strong, and other family members with their own unique personalities and supernatural abilities.
Definitely Harry Potter himself. His magic and his sense of right and wrong would bring a new dynamic to the Winchester world. And then there's Dean Winchester. His tough - guy attitude and his skills as a hunter would be really cool to see interact with Harry. Sam Winchester too, with his intelligence and research skills, could be very interesting when combined with Harry's knowledge of the magical world.
Obviously, the Winchesters, Sam and Dean, are main characters. They are the well - known hunters in the Supernatural world. Then there are often other hunters that the fanfiction writers create or bring in from other parts of the 'Supernatural' universe. These could be hunters with special skills like a tracker who can find any supernatural being by just a small trace left behind.
Stiles is a must - have main character. Then, depending on the direction of the fanfiction, characters like Simon Lewis could be important. Since Simon is a vampire in the Shadowhunter universe, his interactions with Stiles, who is new to this world, could be really interesting. Also, characters like Luke Garroway, the werewolf, might play a role, especially if the story involves the relationships between different Downworlder groups and Stiles' place in all of that.
The main characters would surely include Harry Potter. He is the central figure in the Harry Potter series, and the story is about him being saved. The Winchesters, Sam and Dean, are also key. They bring their own set of skills and personalities from their own show. In addition, characters like Dumbledore might also play a role. He is the wise leader in the wizarding world and could either be aware of the Winchesters' presence or be clueless and later be impressed by their abilities to save Harry.
In many 'Stiles is not human fanfiction', Malia could play a significant role. Given her own complex backstory and her were - coyote nature, she might be able to relate to Stiles in some ways if he's not human. She could either help him adapt to his new state or be in conflict with him. Kira could also be involved. Her kitsune powers and her kind nature might lead her to try and understand Stiles. And the Sheriff, Stiles' father, is bound to be in the story. His relationship with Stiles would be put to the test as he discovers his son is not what he thought he was, and he'd have to deal with his own emotions and the potential danger that Stiles' non - human nature could bring.