It's hard to say. 'Levi x Eren' fanfics are quite common in certain fandoms, but the 'Levi is a criminal' aspect makes it a more specific and perhaps niche sub - genre. If there are a lot of fans who like to see dark or morally ambiguous takes on the characters, it could potentially be popular within that subset of the fandom. However, it also might not be mainstream popular as it goes against the more typical heroic portrayals of the characters.
I haven't come across a Sasha x Connie pregnancy fanfic myself. However, the existence of such a fanfic depends on the creativity of the fans within the relevant fandom. Some fanfic writers might explore this kind of relationship and plot development, but it could also be that not many have delved into this particular scenario yet. You can check fan - made communities and forums related to the source material to see if anyone has written or knows about it.
Maybe Levi is a criminal in the sense that he's part of an underground rebellion against an unjust regime. Eren, who is initially on the side of the establishment, meets Levi and gradually comes to understand his motives. Their relationship could develop as Eren has to decide whether to side with Levi or stay loyal to the regime, all while a romantic connection forms between them.
One idea could be a story where Levi and Eren are on a dangerous mission together. They start off not getting along well due to their different personalities. Levi is strict and methodical while Eren is impulsive. But as the mission progresses, they gradually learn to understand and rely on each other. For example, Eren might save Levi from a Titan in a moment of quick thinking, and Levi in turn teaches Eren some crucial combat skills.
Growth is another theme. Fanfics may show Sasha and Connie growing as individuals within the context of their relationship. They learn from each other, become more mature, and their relationship evolves as they develop new skills and perspectives.
One common theme is growth. Their relationship often reflects how they both grow as individuals. For example, Steven may become more confident in his abilities while Connie becomes more open - minded about different cultures in the world of Gems.
One common theme is friendship exploration. Since Connie and Pearl have different personalities, their relationship can be explored in terms of how they become friends and support each other.
Friendship is a very common theme. Writers often explore how Connie and Sasha support each other through thick and thin. Their different personalities, Connie's more reserved nature and Sasha's boldness, make for interesting dynamics in their friendship.
One key element is the character interaction. Lois and Connie's personalities bouncing off each other can create interesting dynamics. Another is the setting. Whether it's in a modern city or a fictional world, it can shape their relationship. Also, the emotional arc, like how they grow from strangers to friends or more, is important.
Adventure is also quite popular. Many fanfictions take them on exciting journeys, whether it's through a magical forest or in a strange new city. They rely on each other to get through the challenges they face.