His father could be one of the supporters. His father has always been there for Stiles, and he would understand if Stiles was standing up for what's right within the pack. Another possibility is Lydia. She's a smart and powerful character herself, and she might see the value in Stiles' actions and support him.
Well, in such a fanfiction, Stiles might show extraordinary courage. He could use his wits to outsmart the pack when they're being unfair or overly aggressive. Maybe he'll stand up against their unjust decisions regarding how to deal with threats in the town.
There could have been some misunderstandings. Perhaps Stiles overheard a conversation that he misinterpreted. Or some actions of the pack members were misconstrued by Stiles. For instance, if they were joking around but Stiles took it the wrong way and thought they were being mean on purpose, which made him think they hated him.
Scott would be the most likely one. He's Stiles' best friend and the True Alpha. He would never let the Alpha pack harm Stiles and would go to great lengths to rescue him.
There could be other members of Peter's pack such as Derek. Derek often plays an important role in stories related to packs. He might be initially skeptical of Stiles being part of the pack.
Well, obviously Stiles is one of the main characters. He's the one being hurt by the pack. The members of the pack would also be main characters, though we don't know exactly which ones without more context. It could be Scott, as he's often a central figure in the pack. There might also be other characters like Derek who could be involved in either causing the hurt or helping Stiles deal with it.
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.
Well, aside from Stiles, Scott is bound to be a central character. Their friendship is so strong that Scott would immediately start looking for ways to rescue Stiles. Derek Hale is another likely character. Given his past with the alpha pack and his relationship with Scott and Stiles, he would have a role to play. Then there's Allison. Her family's history with the supernatural means she has skills and knowledge that could be useful in rescuing Stiles. She could be involved in the search and rescue operation, using her archery skills and knowledge of the supernatural world to help out.
Perhaps he feels that the other pack can offer him more opportunities for growth. In some fanfictions, the new pack might have access to different kinds of magic or knowledge that Stiles is eager to learn. So, he joins them to expand his skills and understanding.
One way is for the pack members to stand up for Stiles more often. If someone outside the pack is giving him a hard time, they should be there to protect him. Also, they could share their secrets with him, which would show that they trust him. This trust is an important part of any relationship and would help Stiles realize that they don't actually hate him.
Stiles might initially be shocked. He has been a part of the pack for a long time, and Scott kicking him out would be completely unexpected. He could stand there in disbelief, unable to process what has just happened.