A fanfic could explore the relationship between Ooo and Aaa more deeply. Maybe they get into an argument over how to handle a new threat in Ooo, and through their differences, they learn more about each other and strengthen their friendship.
First, think about the personalities of Ooo and Aaa. You could start with a simple situation like them waking up in the morning in Ooo and deciding what to do for the day. This can set the tone for your story.
The timeline of the movie version of Masked Rider Ooo was as follows:
1 " Masked Rider ooo: Heavenly Dao ": December 18, 2006
2. Kamen Rider ooo: Legend of Dragon and Wolf: May 15, 2007
3 Masked Rider Ooo: Hero: November 21, 2007
4. Masked Rider ooo: Shotaro Ishimori: May 18, 2008
5 Masked Rider ooo: Super: December 23, 2008
6 Kamen Rider ooo: Gatsby: May 10, 2009
7 Masked Rider ooo: Ajita: December 7, 2009
8 Masked Rider ooo: Lightning King: May 16, 2010
9 Kamen Rider ooo: Dragon Rider: December 2, 2010
10 " Masked Rider ooo: Jack the Transformed Man ": April 14, 2011
11 " Masked Rider ooo: Ajita 2 ": September 28, 2011
12 Masked Rider Ooo: Gatsby 2: April 22, 2012
13 Kamen Rider Ooo: Beyond Gatsby: September 10, 2012
14 " Masked Rider ooo: Legend of Dragon and Wolf 2 ": May 9, 2013
15 " Kamen Rider ooo: Lightning King 2 ": December 16, 2013
16 " Masked Rider Ooo: Hero 2 ": May 2, 2014
17 " Masked Rider ooo: Shotaro Ishimori 2 ": December 11, 2014
18 " Masked Rider ooo: Ajita 3 ": May 13, 2015
19 Masked Rider ooo: Gatsby 3: December 19, 2015
Masked Rider Ooo: Beyond Gatsby 3: May 27, 2016
Please note that the timeline above is not completely accurate and is only for reference.
Once upon a time in the Land of Ooo, the Vampire King emerged from his dark lair. He was a menacing figure, with his red eyes and long, black cloak. Finn and Jake heard rumors of his return and set out to stop him. But the Vampire King had a plan of his own. He was tired of being feared and wanted to make friends. Finn and Jake were skeptical at first, but as they got to know him, they realized he wasn't all that bad.
Well, in the Adventure Time universe, the King of Ooo is a rather interesting character. BMO might retell Finn's story in its own unique, endearing way. Maybe it would focus on Finn's heroic deeds, like saving princesses or fighting monsters. BMO has a child - like view of things, so it could simplify Finn's complex adventures into a more straightforward and fun narrative.
Well, in the Adventure Time Ice King story, Ice King is a complex figure. He lives in his ice castle. His obsession with princesses is a big part of his character arc. This is related to his past as Simon, who was in love. As Ice King, he's constantly causing chaos in the Land of Ooo. But underneath all that, there's still a bit of the old Simon left, and we can see that in some of his more tender moments, like when he takes care of his penguins.
One common theme is redemption. Many fanfics explore the Ice King's past misdeeds and his attempts to make up for them. For example, he might try to apologize to Princess Bubblegum for all the times he kidnapped her.
Maybe the Vampire King was once a human who was bitten by a powerful and ancient vampire. As he turned, he found himself with new powers and a thirst for blood. Over time, he became more powerful and more feared, eventually rising to be the Vampire King. His main goal was to create a vampire empire in the Land of Ooo.