One interesting storyline could be the exploration of alternate universes within the Underverse setting. Characters might discover new powers or forms in these different realms.
Sans is often a very popular character in Underverse fanfiction. His unique design and mysterious personality make him a favorite for many fans to write about.
Another could be a 'what if' scenario. Like what if a certain character got injured along the way and how it would change the dynamics of the group. This could involve exploring the relationships between the characters as they deal with the unexpected situation.
One interesting storyline could be about the characters' exploration of a new, mysterious part of the Hollows. They might encounter strange creatures and have to use their unique abilities to survive.
There are fanfictions where the Warehouse 13 agents go on a mission to recover an artifact that has been lost for centuries. This artifact could hold the key to saving the world from a great danger. Another type of storyline could be about a character from the Warehouse getting trapped in an artifact - like a mirror where they are stuck in a different dimension. And then the other agents have to find a way to get them out. There are also fanfictions that deal with the internal politics of the Warehouse, with different factions vying for control over the artifacts.
One interesting storyline could be a different take on the relationship between Klaus and Caroline. Maybe in the fanfiction, they team up to face a new and powerful enemy that neither of them could defeat alone. This would bring out new sides of their characters as they learn to trust and rely on each other more.
One interesting storyline could be a reimagining of Batman's first encounter with the Joker in the 1939 fanfiction context. Maybe the Joker starts as a small - time criminal and Batman has to figure out his true motives early on.
One interesting storyline could be the Darkling's redemption. Maybe he realizes the error of his ways and tries to make amends for his past actions, which would be a huge character development shift.
There might be a fanfiction where one of the characters in 2gether gets a once - in - a - lifetime opportunity to study abroad. This creates a lot of emotional turmoil as they have to decide whether to pursue their dreams or stay with their friends and the person they might be in love with.
There might be a fanfiction where a group of Creatures form a resistance against an evil force that wants to control or harm them. This could involve a lot of action, like battles and strategic planning among the Creatures. They might also team up with some humans who believe in their cause.
Another storyline might involve the recruitment of a new member. In the fanfiction, they could introduce a young and highly - skilled fighter who has a unique fighting style. The team is initially skeptical but as they go through missions together, they learn to trust and rely on the new recruit. This could show the growth and evolution of the team dynamic.