Well, an 'Evil Morty' fanfic in the 'Rick and Morty' universe can be really interesting. Evil Morty is such a complex character. In these fanfics, he could be explored further in terms of his motives. Maybe he's tired of being in Rick's shadow or he has some grand plan to take over the multiverse that wasn't fully shown in the show. Fanfics give the writers the freedom to expand on his backstory and what makes him tick.
One more thing that makes these fanfics unique is the way they can twist the relationships in the show. Evil Morty's presence can change the dynamics between Rick and Morty. For instance, Morty might start to question Rick more if he sees what an Evil version of himself is capable of. And Rick might have to reevaluate his relationship with Morty in light of this new threat. This creates a whole new set of story possibilities that are unique to these fanfics.
Evil Morty's origin likely began with his exposure to the many dark and unfair aspects of the multiverse. He was probably fed up with the Ricks' arrogance and control. Maybe he had some unique experiences that made him question his place. He could have started small, observing how things worked and gradually formulating his plans. It's also possible that a particular event, like being mistreated by a Rick, served as the catalyst for his turn to evil.
By putting them in situations where they have to rely on each other. For example, if they are trapped in a dangerous dimension. This would force them to interact and potentially grow closer.
One idea could be that Morty discovers a way to redeem Evil Morty. He tries to show Evil Morty that there's a better way than his villainous path. Morty could use his own experiences of growth and kindness to reach out to Evil Morty.
One main theme is the clash of personalities. Doofus rick is, well, a doofus, while evil morty is calculating. Their interactions often highlight this contrast. For example, in many fanfics, doofus rick will do something silly that throws off evil morty's carefully laid plans.
The Citadel is typically considered historical fiction. It weaves fictional characters and plots within a historical backdrop, offering a blend of fact and imagination. This genre allows for creative exploration while respecting the historical context.