A sense of mystery is also common. The fanfictions usually keep the readers guessing about their true relationship and what will happen next. And there's often a theme of the supernatural. After all, they are nightmare characters, so there are a lot of elements like dark magic and strange powers.
Power struggle can be a theme as well. Sometimes they fight for dominance within the nightmare realm. But at the same time, there's also the theme of friendship or something deeper. They might start as rivals but end up having a strong bond that helps them face the horrors of the nightmare world together.
One common theme is loyalty. They often show how nightmare freddy and nightmare bonnie are loyal to each other in the spooky nightmare world. Another theme is survival. Since it's a nightmare setting, they have to work together to survive against various threats.
There's also 'Nightmare Entanglement'. This fanfiction focuses on the power dynamics between them. It has an interesting plot where they have to team up against a new threat in the nightmare realm. The way the author describes their interactions is quite engaging.
One common theme is the exploration of the dark side. Since they are nightmare - based characters, a lot of fictions focus on their sinister nature.
Another theme is redemption. Some fanfictions depict Killer or Nightmare seeking redemption through their relationship with each other. Maybe Killer wants to break free from his more violent tendencies, and Nightmare plays a role in that journey. It's an interesting way to explore their characters' depth.
Power dynamics is another theme. Given that Ink has his own set of powers related to creation and Nightmare has his dark powers, fanfictions often explore how these powers interact. Who is stronger? How do they use their powers when they are together? These are the questions that are often explored in the 'ink x nightmare fanfiction'.
One common theme is the struggle between good and evil. Since Nightmare is often seen as more of an antagonist and Error has his own chaotic nature. Another theme is the idea of redemption, as in some fictions, they try to find a way to break free from their 'evil' personas. And of course, friendship or a strange kind of alliance is also a theme, despite their differences.
Another theme is redemption. Sometimes the fanfiction might explore the idea of Nightmare being redeemed through his relationship with Cross. It could show how Cross's positive influence might change Nightmare for the better, which is an interesting and complex theme to explore.
One common theme is the exploration of duality. Since Dream and Nightmare are opposites, many fanfictions explore how they are two sides of the same coin. For example, how Nightmare might have some good in him despite his dark nature, and vice versa for Dream.
One common theme is the exploration of darkness. Since both characters have rather menacing aspects, fanfictions often delve into the darker sides of their existence and how they interact within that realm of darkness.
One common theme is the power struggle between them. Since both Error and Nightmare are quite powerful in the Undertale - inspired universe, their relationship often involves jostling for dominance or respect.
Friendship is a common theme. They might be depicted as really good friends who support each other through various challenges in their world. Another theme could be adventure, where they go on exciting quests together.