A plot idea could be a 'what if' scenario. What if the main characters had met in a different setting before the events of the original story? This could lead to a completely different relationship dynamic and story arc.
One idea could be exploring the backstories of the minor characters in more detail. For example, the local fisherman who always gives the main character a friendly nod. Another could be a time - skip scenario where the characters reunite after a long time apart.
Maybe a fanfic where the main event in 'it happened one summer' is re - imagined from a different character's perspective. Like seeing it through the eyes of the antagonist. This could add a whole new layer of depth to the story.
One idea could be about two boys who are initially rivals at the gay summer camp but then gradually fall in love as they compete in various camp activities like a canoe race or a talent show. They start to see each other's good sides and realize their feelings are more than just friendly competition.
One idea could be that Summer's brother has a unique semblance that he has to keep hidden from the enemy. For example, it could be a semblance related to time manipulation, which is extremely powerful but also very dangerous if misused. He might be on a journey to discover more about their family's past and the secrets it holds, which could be linked to the greater mysteries in the RWBY world.
One idea could be exploring a different ending where Belly doesn't end up with Conrad but instead realizes she has stronger feelings for Jeremiah. Maybe she and Jeremiah travel the world together during a gap year, having adventures and deepening their relationship.
Maybe Marinette goes to a summer art camp and Adrien is also there. They work on a big art project together and their feelings for each other grow as they share their creativity and passion for art. During the summer nights, they stargaze and have deep conversations.
One idea could be exploring Harry's training in magic during that summer. Maybe he discovers a new spell or a magical object that gives him an edge for the upcoming year at Hogwarts. Another could be focusing on his relationships, like his friendship with Ron and Hermione growing deeper as they secretly plan for the challenges ahead in Year 5. Or perhaps Harry uncovers a mystery in the wizarding world that is related to the events that will unfold in Year 5, such as a hidden connection to Voldemort's past actions.
The main plot likely involves a story that unfolds during a particular summer. Maybe it's about love, self - discovery, or some kind of adventure that takes place during that season.
The summer dragon could be the key to saving a kingdom that is suffering from an eternal summer. A group of adventurers sets out to find the dragon and convince it to use its power to restore the normal cycle of seasons. Along their journey, they face many challenges like treacherous terrains and other dangerous magical beasts.
One idea could be a time - traveling adventure where Summer and Morty end up in a parallel dimension where their roles are reversed. Morty is the confident, popular one and Summer is the nervous sidekick for a change.
One plot idea could be a character from the All for One world somehow ending up in the Naruto universe and having to adapt to the chakra system. Maybe they try to steal chakra powers like they steal quirks in their own world.
A great plot idea for a RWBY Summer writing fanfic is to explore Summer's relationship with a mysterious character. Maybe there was someone she met during a summer festival who had a connection to an ancient power. As she gets closer to this person, she discovers that there are dark forces at play trying to use this power for evil. Or you could write about Summer's attempt to break a summer - long curse that has been plaguing a small village.