Character development is crucial. In a good fanfic, we can see how Stiles evolves as he deals with the void. Maybe he starts off confused and scared but gradually becomes more in control. Also, the relationship dynamics with other characters need to be well - written. If there are interactions with his friends, they should be believable and add depth to the story. It could show how his friends react to the changed Stiles, whether they try to save him or are afraid of him.
The atmosphere of the void should be well - described. Since the void is a rather abstract and mysterious concept, a good fanfic will use vivid language to bring it to life. It could describe the void as a dark, swirling mass of energy that seems to have a mind of its own. The fanfic should also have a clear theme, like the battle between good and evil within Stiles as he struggles with the void's influence.
A good void stiles fanfic should have a strong plot. For example, it could explore how the void changes Stiles' personality and abilities in a unique way. It should also keep the essence of the original characters, like Stiles' intelligence, even when he is under the influence of the void.
Another great one is 'Into the Void with Stiles'. It starts with Stiles being pulled into the void accidentally. The author does a great job of describing the strange and otherworldly environment of the void and Stiles' struggle to find his way back while also uncovering secrets about the void itself.
One characteristic is the transformation aspect. Stiles being turned into a cat brings a unique twist to the story. Another is the different interactions. As a cat, Stiles has new ways of communicating and interacting with other characters. And often there's a sense of mystery, like how he'll get back to his normal form.
The allure of Void Stiles fanfiction lies in the fact that it often delves into the psychological aspects of the character. He's a character full of mystery and conflict. Fanfictions can explore his inner turmoil, his relationships with other characters in new and exciting ways. For example, a fanfiction might explore how he would interact with a character who was able to see through his facade. This exploration of uncharted territory in the character's story makes it really interesting to read.
Character development is also crucial. As Void Stiles interacts with new characters from the crossover, he may change or they may influence him. And vice versa. In some fanfictions, he might start to show a bit of humanity again because of a particular character he meets.
Fanfiction.net might also be a good place. There are numerous Teen Wolf - related fanfictions there. You need to search specifically for Void Stiles fanfiction. However, the quality can vary, so you may have to browse through a few to find the really good ones.
One common theme is the power dynamic. Since Void Stiles has a certain kind of dark power, exploring how that power affects the relationship with the reader - insert character is often seen. For example, the reader might be initially afraid but then grow to understand and even be attracted to that power.
One popular Void Stiles fanfiction is 'The Void Within'. It delves deep into the darker aspects of Void Stiles' character. Another great one could be 'Void's Ascent' which focuses on his journey in the supernatural world. There's also 'Facing the Void' that explores his relationships with other characters while being in the Void state.
You can try websites like Archive of Our Own (AO3). It has a large collection of fanfictions, including many about Void Stiles. Fanfiction.net is also a good place to look. There are likely to be some great Void Stiles fanfics on there as well.
In Stiles werewolf fanfiction, Stiles is often depicted as intelligent. He uses his smarts to navigate the complex world of werewolves. For example, he might figure out a way to break a werewolf curse using his knowledge.
There's also 'Void's New Realm'. In this fanfiction, Void Stiles crosses over into a world filled with magic and has to navigate through a whole new set of rules and power dynamics. The story does a great job of exploring how Void Stiles would adapt in such a strange place.