One common theme is loyalty. Armin and Erwin are both extremely loyal to their comrades and to each other. In fanfics, this loyalty often becomes a central aspect of their relationship. Another theme is leadership. They are both leaders in their own ways, and fanfics might explore how they lead together or support each other's leadership.
One popular 'Attack on Titan Armin x Erwin fanfic' is 'The Bonds Beyond the Walls'. It delves deep into their relationship, exploring how they support each other during the tough times in the Survey Corps. Another great one could be 'Shared Visions' which focuses on their strategic minds working together and how that draws them closer on an emotional level.
One popular theme is the growth of their relationship. Starting from distrust or indifference and evolving into a deep friendship or something more. Another theme could be them facing challenges together, like a particularly difficult Titan attack where their combined skills are put to the test. Also, the theme of sacrifice might be present, where one is willing to sacrifice for the other in a life - or - death situation.
One popular trope is the 'enemies to lovers' dynamic. Given their positions as former enemies in the main story, it's common for fanfictions to explore how they transition from hostility to love. Another trope is the 'hurt/comfort' where, for example, Annie might be injured or in distress, and Armin is there to comfort her, which deepens their bond.
One popular theme is their friendship evolution. As they grow up in the dangerous world of Attack on Titan, their bond changes and deepens. Another theme could be sacrifice. How far would Eren or Armin go to protect each other? And there's also the theme of trust. Given the complex and often deadly situations they face, trust between them is crucial and can be a major focus in fanfiction.
In many Attack on Titan fanfics about Levi and Erwin, their relationship is often complex and deep. Levi respects Erwin's leadership skills and strategic mind. Erwin, on the other hand, trusts Levi's combat abilities. Their relationship can be seen as a partnership that is crucial for the Survey Corps. They support each other in the face of the Titans and the many challenges within the walls.
One popular trope is the 'unspoken understanding' between them. They can communicate with just a look during crucial moments in battle or decision - making. Another is the 'protective Levi' trope, where Levi is always ready to defend Erwin from any threat, whether it's a Titan or a political enemy within the walls.
Another theme is growth. They both grow as characters throughout the series, and in fanfictions, this growth is sometimes shown in relation to their relationship. Maybe Armin becomes more confident and Mikasa learns to open up more because of their bond.
Well, in many fanfics, a popular plot is when Eren and Armin have a disagreement about how to deal with the Titan threat. Eren might want to be more aggressive, while Armin advocates for a more cautious approach. This leads to a rift between them for a while. But as the story progresses, they realize they need each other and come back together stronger. Another plot could be them exploring a new area outside the walls and encountering new types of Titans or mysteries that they have to solve together.