There's also a chance that Papyrus would feel a sense of pride. If Sans is fighting for a noble cause, Papyrus could look on with admiration, thinking that his brother is being brave and strong. He might cheer Sans on from the sidelines, yelling words of encouragement.
Papyrus might be initially shocked. He's used to Sans being more laid - back, so seeing him in a fight could be quite a surprise. His eyes would widen and he might gasp.
He could also feel worried. Since Sans is his brother, Papyrus would be concerned for his safety. He might start pacing back and forth, muttering to himself about how to help Sans if things go wrong.
Another plot twist could be that Papyrus realizes the fight is all an illusion. In the fanfiction, he might see through some sort of magic or mind - control that was making Sans fight. So, he then has to figure out how to break the illusion and save Sans from this false battle.
Maybe Papyrus challenges Sans to a friendly battle to figure it out.
One great idea for a fanfiction could be a story where Underswap Sans and Underswap Papyrus go on an adventure in the Underground. Maybe they encounter a strange new monster that no one has ever seen before. They have to use their unique abilities to figure out how to deal with this new threat.
Well, in 'underfell sans x papyrus fanfiction', their relationship is a key aspect. It can vary greatly depending on the author's interpretation. Some may focus on the loyalty between them, despite the cruel environment of Underfell. Others might explore how their personalities clash or complement each other. For example, Sans' cynicism in Underfell might contrast with Papyrus' more naive side, creating interesting storylines and character developments.
A great idea could be a story about their daily adventures in the Underground. For example, they could be on a quest to find a rare ingredient for a new recipe Papyrus wants to try. This would focus on their brotherly bond and Papyrus's enthusiasm for cooking, while Sans tags along with his laid - back attitude.
One characteristic is the strong focus on their brotherly relationship. Fanfics often show how Sans and Papyrus rely on each other, like in how Sans might be the more laid - back one while Papyrus is full of energy and enthusiasm, and they balance each other out. Another is the use of the unique Underground setting. It provides a backdrop for their adventures and interactions. For example, they might be dealing with other monsters while also strengthening their own bond.
Common themes in 'underfell sans x papyrus fanfiction' include power dynamics. Since Underfell is a harsher world, there might be a shift in the power balance between Sans and Papyrus. Additionally, redemption can be a theme. Maybe one of them has made mistakes in this unforgiving world and is seeking redemption. Also, the theme of trust, as they need to trust each other to survive in such a difficult environment.
Sans is often characterized by his laid - back attitude and powerful abilities. Underswap Papyrus, on the other hand, has his own distinct personality which is different from the regular Papyrus. He may be more serious or have different quirks, and their interactions as the main characters drive the story forward.
There are many alternatives. You could look for fanfictions that focus on their platonic relationship, like them going on a quest together in the Underground. Another option is fanfictions that explore their individual character growth outside of a romantic or inappropriate context.
I don't recommend seeking out 'lemon' fanfiction, especially for undertale sans x papyrus. Their relationship in the original game is more of a brotherly one. If you want to explore fanfiction about them, there are plenty of non - 'lemon' ones that focus on their adventures, character development, and the unique bond they share in the Undertale universe.