Well, in this kind of fanfiction, a common theme might be the conflict between family expectations and their own feelings. The sisters in Johnny Test are part of a family, and having a romantic relationship between them would likely go against what their family would expect. Also, the theme of acceptance, both from themselves and potentially from others if their relationship were to be known, could be prevalent. It's about how they handle the situation in a world where such a relationship is not the norm. Additionally, there could be a theme of growth as they learn to understand their emotions better through this experience.
There might be some really good 'Johnny Test Sisters Falling in Love' fanfiction. Some of them could focus on how the sisters' relationship changes when they start to have romantic feelings. It could explore new dynamics within the family and with Johnny himself. However, the quality can vary a lot. Some might be well - written with great character development, while others could be more for fun and not as in - depth.
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.
One common theme is identity. Johnny has to figure out who he is now as a girl. Another theme is family reactions. His family has to deal with this new version of Johnny, and it often leads to comical or heartwarming moments. For example, in some fanfics, his dad is completely clueless at first.
A common theme is the transformation of Johnny into a vampire. It often explores how he deals with his new powers and the changes in his relationships, like with his sisters. Another theme could be the conflict between vampires and humans in the Johnny Test universe.
Adventure is also a big theme. Since Johnny is always getting into some sort of trouble or on a new quest, the OC gets dragged along. This can range from exploring strange places in their town to dealing with wacky inventions gone wrong.
One common theme could be overcoming obstacles. Maybe they come from different backgrounds or have different goals in life, and the fanfiction focuses on how they overcome these differences to be together.
Often, his sisters might play a role in the 'hurt' scenarios. Maybe they accidentally contribute to Johnny getting hurt while trying to stop one of his wild schemes. Another element could be the reactions of his family and friends to his injuries, which can add emotional depth to the story.
Well, a theme that can't be ignored is the theme of family. Johnny has his own family in the original show, and Gill could be incorporated into that family dynamic in interesting ways in fanfiction. Maybe Gill becomes like a part of the family and they all have to adjust to his presence. There could be heartwarming and funny stories around this theme.
In a Johnny Test love potion fanfiction, the love potion could be part of a science fair project. Johnny's intention was to create a potion that would make people like each other more in general. But when he tests it on himself, he falls in love with the concept of time travel (because he was thinking about it right before taking the potion). So he starts trying to build time - travel machines to be closer to what he loves, and his family has to stop him before he causes a time - related disaster.
One common theme is redemption. Loki is often portrayed as a character seeking redemption through love. His love for someone can be the catalyst for him to change his ways and become a better version of himself. Another theme is the struggle between his nature as a trickster and his new - found feelings. He has to decide whether to be true to his old self or embrace this new emotional side.