What are the common themes in sans x gaster fanfiction?

One common theme is mystery. Since both Gaster and Sans have mysterious backstories in the original game, fanfictions often explore and expand on these mysteries, especially in relation to their relationship.

A sense of otherworldliness is common too. Since Gaster Sans is from a rather strange and unique universe, the fanfictions often play with the idea of the reader being in a very different, almost alien world. This can lead to themes of adjustment, as the reader tries to fit into this new world while being in a relationship with Gaster Sans.

One common theme could be the exploration of their relationship in the context of the outertale universe. It might involve how they interact with the unique settings and other characters in that AU.

One common theme is loyalty. They are both important figures in the monster world, and stories often explore how loyal they are to each other and to their respective causes.

Well, a major theme is the exploration of the unknown. Gaster's nature and his past are often shrouded in mystery in the original source, so in fanfiction, the reader and Gaster might embark on a journey to discover things together. Also, the theme of redemption can be present. Gaster may have some past mistakes or regrets, and the relationship with the reader could be a part of his path to redemption. Additionally, there can be a theme of power imbalance at times, as Gaster might have more knowledge or power, and how the reader deals with that in the relationship is explored.

Often, themes of friendship or rivalry might be present. They might start off as rivals but then develop an understanding or even a friendship. Another theme could be the contrast between their personalities. Lust Sans is known for his more flirty nature while Fell Sans has a more aggressive side, and how these play out in their relationship is a popular theme. Also, in some fanfictions, they might team up to face a common enemy or situation, which is also a recurring idea.

Another theme is friendship or partnership. They often come together to face challenges in the Underground. For example, in many fanfictions, they join forces to defeat a powerful monster or solve a mystery that threatens their world. This theme of unity despite their differences is really appealing.

One common theme is friendship. Since they are from different 'worlds' in the Undertale AU, their journey to become friends is often explored. Another theme is redemption. Sometimes Cross Sans might have a troubled past and Dream Sans helps him find a new path.

Power dynamics is also a frequent theme. Nightmare Sans is often depicted as very powerful, and Cross Sans has his own set of powers. Fanfictions might explore how they use or abuse their powers in relation to each other. It could be a power struggle, or they could end up combining their powers for some greater purpose.

One common theme is power. Both characters are quite powerful in their own right, and fanfictions often explore how their powers interact. Another is the idea of redemption or the lack thereof. Since they are not exactly 'good' characters, some stories might play with the concept of them finding a way to be better. And of course, there's the theme of their relationship, be it a partnership, a rivalry, or something in between.