Another interesting plot could be that the topless robot is actually a vessel for a lost heart. In the world of Kingdom Hearts, hearts are very important. The characters discover that the robot holds the heart of a long - lost Keyblade wielder. They then embark on a journey to restore the heart to its proper place, all while dealing with the usual Kingdom Hearts enemies and challenges.
Perhaps a plot where the topless robot has some sort of connection to the Heartless. It could be that the robot was created by an unknown force to either help or hinder the fight against the Heartless. The characters would then have to figure out its true intentions. For example, the robot might seem menacing at first but turns out to be a key to unlocking a new power for Sora.
One possible plot idea could be a new adventure where the main characters from Kingdom Hearts find themselves in a digital world created by the topless robot. Maybe they have to solve puzzles related to the robot's programming to find their way back to their normal world.
Well, it could potentially be a manifestation of someone's negative emotions, just like how the Heartless are created. Maybe someone in the Kingdom Hearts universe had such strong feelings towards technology or machines that it created this topless robot. It could be a symbol of the struggle between the old magic - based world and the encroaching technology. So, it would fit in as a new type of enemy or ally depending on how its origin story unfolds. It could also have some unique abilities related to technology that the characters have never seen before, like the ability to hack into digital systems in the different worlds.
One idea could be exploring the backstories of the minor characters in the Kingdom Hearts universe. For example, delving into the past of the different Keyblade wielders we only briefly see. Another idea is to create an alternate timeline where Sora makes different choices during his adventures. Maybe he sides with the villains for a while to understand their motives better. Also, you could write a fan fiction focused on the relationship between different worlds in the game, like how the world of Wonderland affects the world of Olympus Coliseum.
One idea could be exploring the backstories of the new characters introduced in Kingdom Hearts 3 in more depth. For example, you could write about how they came to be in the different worlds and what their true motives are.
One idea could be that the Heartless somehow find their way into the Marvel universe and start attacking various locations. The Avengers, being the protectors, team up with Sora and his friends from Kingdom Hearts. They initially have some clashes due to different fighting styles and ways of understanding the world, but eventually learn from each other and combine their powers to defeat the Heartless. For example, Iron Man could use his technology to analyze the Heartless' weaknesses, while Sora uses his Keyblade to directly combat them.
Well, a great plot for a Kingdom Hearts 3 Aftermath fanfiction could involve the relationships between the different characters. Like, how Riku and Kairi's friendship might have evolved. Also, since Xehanort was defeated, there could be a power vacuum. Some villains might try to take advantage of it, and the heroes have to stop them before a new, greater evil rises. It could also show the daily lives of the characters in a more peaceful time, with little hints of the past adventures.
One idea could be that Sora finds himself in a new world where he is surrounded by characters from different Kingdom Hearts realms who all have a strong attraction to him. They compete in a friendly way to go on adventures with him.
One idea could be exploring how the dalmatians' world is connected to the Kingdom Hearts universe in terms of magic. Maybe the dalmatians have a special kind of magic within them that can help Sora in his battles. Another could be a story where the dalmatians are being hunted by Heartless and Sora has to protect them. Also, perhaps there's a secret about the dalmatians' spots that has significance in the Kingdom Hearts lore.
One idea could be creating an OC who is a keyblade wielder from a forgotten world. This OC could be on a quest to discover the secrets of their world's connection to the greater Kingdom Hearts universe. They might encounter classic characters like Sora and Riku and have to prove their worth as a keyblade wielder.
Well, perhaps in this fanfiction, the Organization XIII has a plan to use Elsa's powers for their own evil purposes. They manipulate events in Arendelle to make Elsa feel isolated and out of control. Sora, Donald, and Goofy show up and befriend Elsa, showing her that she can trust others. They then have to battle the Organization XIII members while also dealing with the internal struggles of Arendelle's characters, like Anna's determination to save her sister no matter what.
Perhaps there could be a plot where the Organization XIII members from Kingdom Hearts have an interest in the Relics from RWBY. They start to manipulate events in the RWBY world to try and get their hands on these powerful artifacts. The RWBY characters, suspecting something is amiss, team up with Donald and Goofy who have also arrived in their world. Together, they have to figure out the Organization XIII's plan and stop them before they can steal the Relics.