A lot of these fanfics also deal with the theme of redemption. Nagito has his own complex backstory, and when paired with sans, there can be a story of redemption for Nagito. It can be about him finding a new purpose or a way to overcome his past through his relationship with sans. And then there's the theme of discovery. Discovering new things about each other, their powers, and their worldviews.
One common theme is the exploration of hope and despair. Given Nagito's obsession with hope and Hajime's more down - to - earth nature, fanfics often play with these concepts in relation to their relationship.
Well, 'Parallel Universes' is also a great one. In this fanfic, the idea of different universes brings sans and nagito together. It's filled with a lot of exciting plot twists as they navigate through the challenges of co - existing in a world that's not quite what they're used to. The character development is really well - done in this one too.
One common theme is friendship. Despite their differences from different AU's, they often form a unique bond.
One common theme is the struggle between good and evil, as Dream Sans is often associated with positive aspects and Nightmare Sans with negative ones. Their relationship in fanfics can explore how they deal with their opposing natures.
One common theme is redemption. Chara is often portrayed as a character in need of redemption, and Sans is sometimes the one who helps them on that path. Another theme is the exploration of different AUs, as it allows for a lot of creativity in how their relationship can develop.
One common theme is the exploration of their different personalities coming together. Sans is usually depicted as cool and collected while Alphys is more nerdy and anxious. Their relationship often involves Alphys learning to be more confident with Sans' support. Another theme is the use of the Underground setting as a backdrop for their relationship to develop, like dealing with the other characters in that world.
One common theme is the exploration of good and evil. Flowey has done some rather cruel things, while Sans is often seen as a more 'good' character. Fanfics might play with the idea of Sans trying to redeem Flowey or vice versa.
One common theme is redemption. Often, Flowey, with his complex past, is on a journey towards redemption, and sans can play a role in that. Another theme is friendship in unlikely places, as they are two very different characters.
Many fanfictions explore the idea of redemption for Nagito through his relationship with Hajime. Since Nagito has his own set of issues and actions in the original story, the fanfictions sometimes show Hajime as a positive influence that helps Nagito become a better person. Also, the theme of mutual support is quite common, with them relying on each other both emotionally and in terms of dealing with the threats around them.
One common theme is redemption. Since Asriel has a complex past in Undertale, many fanfics use the relationship with Sans to explore his path to redemption. Another is friendship. Despite their differences, they can form a unique bond.