One common theme is redemption. Annie has done some pretty bad things in the series, and in many fanfics, Armin is a key figure in her journey towards redemption. Another theme is love in the face of chaos. Given the world they live in, filled with Titans and danger, their love is often portrayed as something that can survive and even thrive in such a harsh environment. Also, the theme of understanding each other's pasts is quite common. They both have complex backstories, and fanfics often explore how they come to understand and accept each other's past traumas.
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 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.
Some fanfics might explore a romantic relationship between them in a more secretive or forbidden way. Given the military setting and the overarching plot of Attack on Titan, their relationship might be something they have to hide. This adds an element of tension and drama to the story, as they navigate their feelings while also dealing with the threats of the Titans and the politics within the walls.
Love and acceptance are also big themes. They come from different backgrounds and have different personalities. So, their journey to accept each other and fall in love is often explored. A lot of fanfics show how they break down the barriers between them to be together.
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.
Sure. One popular 'Attack on Titan Armin x Annie fanfic' is 'The Unspoken Bond'. It delves deep into their relationship post - the main events of the series, exploring how they heal together and come to understand each other on a new level. Another great one is 'Shared Horizons' which focuses on their adventures side by side, facing new threats and relying on each other's strengths. There's also 'Hearts in the Ruins' which is a more emotional take on their relationship, dealing with the traumas they've both faced and how they find solace in one another.
The contrast between their characters. Annie is strong, stoic and a bit of an enigma, while Armin is more cerebral and empathetic. Their interactions can be really fascinating to explore in fanfiction.
One popular story might be about their unlikely friendship evolving during their time in the military training. It could explore how Annie's tough exterior starts to crack in the presence of Armin's gentle and intelligent nature.
One common theme is the exploration of the blurry line between friend and foe. Since the Female Titan is initially an enemy, fanfictions often delve into whether she can become an ally through her interactions with Armin. For example, Armin might try to convince her to side with the humans.
One common theme is self - discovery. As they interact, both Annie and Armin often discover new things about themselves. Another theme is the power of friendship. Their relationship, whether it's a budding romance or a deep friendship, is often shown to have a strong impact on their lives.