One interesting plot could be Star and Marco exploring new dimensions together in the future. They might encounter strange creatures and have to use their combined powers to survive.
Maybe a plot where Star and Marco have to deal with a new threat to their kingdoms in the future. This could involve political intrigue and battles. They'd need to rely on their friendship and the allies they've made over the years. For example, they might have to convince some of the more reluctant magical beings to join their side against the common enemy. And during this process, their relationship could also evolve in unexpected ways.
Another plot could be that in the future, Star and Marco accidentally break a powerful magic spell that was keeping an ancient evil at bay. They then have to race against time to fix their mistake, traveling to different parts of the magical universe to gather the necessary ingredients for a new spell.
One interesting Star and Marco fanfiction could be about their adventures in a new dimension. Maybe they discover a land full of magical creatures that are different from anything in Mewni or Earth. Another could be a story where they have to work together to solve a mystery in Echo Creek that involves a strange spell.
Some fanfictions might focus on the daughter's relationships. She could have a best friend who is from a completely different background and they go through typical coming - of - age situations together. Or, there could be a love interest story where she has to deal with the complications of having a famous and powerful set of parents while falling in love with someone not as well - known or powerful.
Janna is another popular character. She's known for her mischievous nature. In future fanfiction, she could be involved in some wild adventures with Star and Marco, perhaps using her unique skills and knowledge to help them out of tight spots or getting them into even more trouble.
Some interesting ideas include the alteration of their character arcs. A gender - swapped Star might have different goals in life. Maybe instead of focusing on princess - like things, a male Star could be more interested in proving his strength in a more traditional masculine way. For Marco, if he were female, her relationship with Jackie could be very different. It could be more of a sisterly bond or a friendly rivalry. And the overall tone of the story could change too. It might become more about breaking gender stereotypes in the magical world they live in.
Another plot could involve the other characters' reactions to Star's Mewberty. For example, Jackie might be a bit jealous or confused about the new dynamic between Star and Marco. And Janna could be intrigued and try to use the situation to her advantage in some comical ways.
One idea could be that Star has a Mewberty episode in a new dimension while Marco tries to find a way to calm her down using his knowledge of her previous Mewberty forms. Another could be a story where Marco accidentally triggers Star's Mewberty transformation during a school event, and they have to deal with the chaos together while also hiding it from others.
One interesting plot could be Future Trunks arriving in a new timeline where lemons have some sort of magical power. He has to figure out how to deal with this new element while also protecting the timeline from threats. Another plot might involve Future Trunks having an encounter with a character who is obsessed with lemons, and their strange relationship leads to various adventures. And there could be a plot where Future Trunks uses lemons as a symbol to inspire hope in a dark and desolate future, like using lemon - scented items to remind people of better times.
One interesting plot could be Peter seeing a future where his friends are in danger and he has to figure out how to prevent it. He might struggle with whether to tell them or try to handle it alone.
One interesting plotline could be an alternate version of what happened during the Blood Moon Ball. For example, Star and Marco might have had a more in - depth conversation about the implications of the Blood Moon's magic. Another could be a story where the events of the Blood Moon Ball are re - imagined from the perspective of a minor character who was present at the ball.
Marco could be a fan, a writer, or a character created specifically for this concept. Without more context, it's hard to say exactly who he is.