Perhaps a fanfic set in a modern - day world where these characters are reimagined as ordinary people. Cynder could be a hacker, using her skills in a digital world similar to her stealth in the original setting. Ember is a bodybuilder, Sheila a parkour enthusiast, Elora a university professor of ancient history (relating to the magic in their original world), and Bianca a businesswoman. They all get caught up in a mystery that requires all of their skills to solve.
A fanfic could focus on the relationships between these characters. Maybe there's some initial tension between Cynder and Sheila due to their different personalities, but as they face challenges together, they learn to understand and respect each other. Ember could be the one who tries to keep the peace among them all. Elora might be the one who discovers a hidden prophecy about their group, and Bianca has to figure out how to use it to their advantage.
They could have an adventure in a lost ancient city. The city is filled with traps and puzzles. Cynder's ability to sense danger would help them avoid the traps. Ember could use her brute force to move heavy objects blocking their path. Sheila's nimbleness would be useful for climbing over obstacles. Elora would decipher the ancient inscriptions on the walls to find the way forward, and Bianca would keep track of their supplies and make sure they stay on schedule.
A fanfic could center around Ben teaching Melinda a new and powerful spell. He might be an expert in a certain type of magic that she wants to learn. As they practice, they accidentally create a magical mishap that they then have to fix together. This could lead to a deeper understanding between them.
One good 'Cynder and Ember' fanfic could be 'The Adventures of Cynder and Ember' which explores their friendship in a new magical world. It has great character development.
You can try fanfiction.net. It has a large collection of fanfics from various fandoms, including 'Cynder and Ember' ones.
One idea could be exploring how Cynder's pregnancy affects her relationships with her friends and allies. Maybe she has to step back from certain dangerous tasks, causing some tension within the group. Another could be focusing on the preparations for the new arrival, like building a safe place for the baby in a fantastical world. And perhaps there could be a mystery surrounding the nature of the baby, like it having some special powers or a unique heritage.
One idea could be that they start by re - establishing their bond after some great adventure. They might go on a journey to a magical place that is said to strengthen the connection between dragon pairs. As they explore this place, they gradually realize their feelings for each other are more than just friendship and decide to mate to continue their dragon lineage.
One interesting fanfic concept is that Danny and Ember are forced to work together to save the Ghost Zone from a powerful, ancient evil. They must combine their powers and knowledge. Danny's scientific knowledge about the Ghost Zone and his powers, along with Ember's knowledge of the more mysterious and musical aspects of the Ghost Zone, could lead to a great adventure and a deepening of their relationship.
A fanfic could explore what would happen if Catwoman found out Batman's true identity before he was ready to reveal it. Maybe she uses this knowledge to try and protect him from a threat that is specifically targeting Bruce Wayne, and in the process, their relationship takes an unexpected turn.
One idea could be a story where Naruto and Haku team up on a special mission. They could start off not trusting each other much, but as the mission progresses, they come to respect and rely on one another's skills. For example, Naruto's brute strength combined with Haku's stealth and water jutsu could make for an interesting dynamic in overcoming the mission's obstacles.
Another fanfic concept could be a time - travel one. Stiles accidentally sends himself, Adrian, and Harris back in time. They end up in a different era, say the 1920s. Now they have to figure out how to get back while also dealing with the cultural shock and the new rules of that time period. And along the way, they might even change some historical events without realizing it.