One interesting storyline could be exploring the backstories of the minor characters in the Masters of the Universe universe. For example, delving deeper into the origin of Orko, his life on his home planet before coming to Eternia. Another could be a story where He - Man and Skeletor have to team up against a greater evil that threatens both their interests. This would flip their usual dynamic on its head.
Some fanfictions focus on the relationships between the characters. For instance, a story could be about the friendship between Teela and He - Man. It could show how their bond develops over time, through various battles and challenges. It might also include some internal conflicts for Teela, like her feelings for He - Man while also trying to be an independent and strong warrior in her own right.
One interesting storyline could be a new hero emerging from a small town. This hero has a unique power that the Avengers initially mistake for a threat. So, there's a lot of tension and action as the Avengers try to figure out if this person is friend or foe. Eventually, they discover the hero's good intentions and they all team up to face a greater threat like an alien invasion.
One interesting storyline could be about an alternate version of Sam and Dean where they are vampires instead of hunters. It would completely flip their roles and moral compasses.
There could be a fanfiction that delves into the concept of He - Man facing a new, more powerful enemy that challenges his very understanding of good and evil. This enemy might not be as straightforward as the ones he has faced before, making him question his own methods and values.
One interesting storyline could be where Steven's gem powers interact with the magic in the Undertale world. For example, his ability to heal might have a unique effect on the monsters in Undertale. Maybe he could heal some of the more damaged monsters and in turn, they help him understand their world better. Another could be a story where the characters from both universes team up to face a common threat. The Sans and Papyrus from Undertale could join forces with Steven and the Crystal Gems to fight against a powerful enemy that is a threat to both their worlds. It would be really cool to see how their different fighting styles and powers work together.
One interesting storyline could be about a new and powerful character emerging in Universe 9. This character might have a unique ability that challenges the existing power hierarchy. For example, they could control a type of energy not seen before in the Dragon Ball universe.
A really cool storyline in a Naruto - DC crossover fanfiction could be the idea of Naruto characters training DC heroes in the ways of chakra. Superman, for example, could learn to control chakra and use it to enhance his already superhuman abilities. Or, a story where the Justice League has to deal with the political intrigue of the Hidden Villages in Naruto's world. It would be a clash of two very different political systems. Also, a storyline where a Naruto character like Sasuke becomes a sort of anti - hero in the DC Universe, causing chaos among the heroes and villains alike could be fascinating.
One interesting storyline could be about how the Jedi and Sith ideologies would play out in a modern - day Earth setting. For example, the Jedi's code of non - attachment might be a struggle for people in a consumer - driven society. Another could be the discovery of a hidden 'Star Wars' - like civilization on Earth, and how it interacts with the known world.
Well, there are often storylines where the moral compass of the mirror universe characters is explored. For instance, a story might focus on a character from our normal universe getting stuck in the mirror universe and trying to adapt to the cut - throat, amoral environment while still holding onto their own values. They could try to influence the mirror crew to be less brutal. Another idea could be a power struggle within the mirror Enterprise crew, with different factions vying for control over the ship and its resources, which would lead to all sorts of betrayals and double - crosses.
Well, a really cool storyline might be that in the all - female universe, Harley Quinn discovers a hidden society of female superheroes. At first, they're suspicious of her because of her villainous past, but she convinces them that she wants to change. Together, they fight against a new threat that is trying to destroy both the villain and hero worlds. It could involve Harley using her unique skills and the female superheroes using their powers in a combined effort. And there could be some great character development along the way as Harley tries to fit into this new world of heroes.
One interesting storyline could be about how the Voyager crew has to adapt to the harsh and cutthroat rules of the mirror universe. For example, they might have to deal with power struggles within their own ranks as they are influenced by the mirror universe's values.