One common theme is friendship. Since ace and buttercup are characters, their relationship can be explored in terms of how they become friends, support each other through various situations. Another theme could be adventure. They might go on adventures together and face different challenges.
One common theme could be the changes in Buttercup's character due to pregnancy, like becoming more protective or vulnerable. Another might be the reactions of the other characters in the story towards her pregnancy.
One common theme could be the exploration of their different personalities. Buttercup is tough and feisty, while Butch is also rough - around - the - edges. Their interactions based on these personalities, like a sort of 'opposites attract' situation, are often explored. For example, in some fanfictions, they might start off as rivals and then develop feelings for each other.
Another theme is the exploration of power. Since they both have superpowers, fanfictions often play with how their powers interact and how they use them together or against each other in different situations. For example, in some stories, they combine their powers to defeat a common enemy.
Transformation is also a common theme. Buttercup might be on the verge of becoming a vampire herself, or she could be trying to resist the allure of the vampire life that Butch represents. This internal struggle can be a major part of the story. And of course, there's the theme of good vs evil. If Butch is a vampire, he may be trying to fight his own vampiric instincts which are often associated with evil, while Buttercup could be the moral compass guiding him.
A frequent theme is the discovery of one's true self. Buttercup might find out new things about herself in relation to Butch's vampire nature, like hidden strengths or fears. And of course, there's the theme of the supernatural world. Fanfictions usually explore the rules of the vampire world, such as their powers, weaknesses, and the hierarchies within it, and how Buttercup and Butch interact with this world.
A common theme is the exploration of their different personalities coming together. Butch is often portrayed as tough and Buttercup as strong - willed, so their relationship can be about two forces colliding in an interesting way.
One common theme could be their unique dynamic as superheroes. Their powers and how they interact during battles or while saving the day might be explored. Another theme could be their personal growth and how they influence each other's development.
Superpowers and science - fiction elements are likely to be themes as well. Johnny has his own set of adventures often related to his sister's inventions, and Buttercup has her superpowers. Fanfiction could explore how these elements interact when the two characters are brought together, like perhaps using science to enhance or counteract superpowers.
A theme that frequently shows up is redemption. Princess Morbucks, being a bit of a villain in the original, might be on a path to change in these fanfictions, and Buttercup could play a role in that. Another theme is friendship or the possibility of it. Since they start from different sides, the idea of them becoming friends or allies is explored often. There are also stories that focus on competition between them, like who can outdo the other in a particular task or in winning over a certain character's approval.
One common theme is the exploration of their different personalities. Buttercup is tough and feisty, while Butch has his own charm. Their clashing and then coming together is often explored.