One common theme is friendship. Despite their rather dark and spooky nature in the original concepts, fanfictions often explore a deeper bond between Jeff and Hoodie. Another theme could be adventure, where they go on some sort of journey together, whether it's in a haunted world or something else.
A theme that pops up a lot is the development of an unlikely relationship. The reader, who might be an ordinary person, and Hoodie, with his secretive nature, form a bond. Also, there's the theme of trust. How the reader comes to trust Hoodie despite his often enigmatic behavior is a big part of many fanfictions. In some stories, there's also the theme of sacrifice, where Hoodie might sacrifice something for the reader.
Another theme is mystery. Because both characters have an air of mystery about them, fanfictions often play on that, creating stories full of secrets and revelations. For example, they might be on a mission together and there are hidden motives or backstories that gradually unfold.
Survival is also a big theme. In the dark and dangerous world they live in, they have to rely on each other to survive against other threats. For example, there could be rival groups or supernatural entities that they need to fend off together.
Well, you can check out Archive of Our Own (AO3). There are often some really creative Jeff x Hoodie fanfictions there. Just search for the tags related to them, and you might find some great stories.
A third common theme is the psychological aspect. Writers like to play with the minds of these characters. How does Jeff's insanity interact with Slenderman's otherworldly presence? Fanfictions often explore this, looking at how their mental states affect their actions and their relationship with each other. There can be a lot of mind - games and power struggles within the stories.
One common theme is friendship. In many Jeff x Ben fanfictions, they start off as acquaintances or even enemies and then develop a deep friendship. Another theme is survival. Since they often exist in rather dangerous or strange settings, they have to work together to survive. For example, in some stories, they are in a world full of monsters and they rely on each other's skills.
The theme of trust is quite common. Since they might come from different backgrounds or have had different experiences, building trust is crucial in their relationship in these fanfictions. Additionally, the theme of sacrifice often appears. They might have to sacrifice something for the sake of the other or for their relationship to survive. For instance, one might sacrifice a personal ambition to be with the other.
A common theme is the exploration of their psychological states. Given their rather dark and complex natures, many fanfictions dig into how they think and feel. Another theme is the idea of redemption or change. Some stories show one or both of them trying to move away from their more violent tendencies.
One common theme is the struggle with their age difference. In many fanfictions, they have to deal with how society views their relationship due to Jeff being older. Another theme is their academic competitiveness translating into their relationship. For example, they might compete over who is smarter in a certain subject while also having romantic feelings for each other.
Friendship is a common theme. Many fanfictions might explore how Randy and Jeff become friends and the different situations that strengthen their bond. Another theme could be adventure, where they go on exciting journeys together.