Obviously, Sans and Papyrus are the two main characters who we already know well from the original Undertale. They have distinct personalities that will play a big role in how they interact with Gaster. Gaster, on the other hand, is the enigma. His presence will likely drive the story as Sans and Papyrus try to figure out who he is now and what he wants, so he's also a main character in this fanfiction.
Well, it could be about Gaster suddenly reappearing in the lives of Sans and Papyrus. Maybe he has some important knowledge or a mission for them. For example, he might need their help to fix something in the Underground that's going wrong.
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.
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.
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.
One common theme is mystery. Since both characters have elements of mystery in their original lore, fanfictions often explore that further. Another theme is power dynamics. Given their different abilities, how they interact in terms of power is often explored. And friendship or a deeper connection is also a common theme as writers like to explore the relationship between these two unique characters.
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.
Obviously, Gaster and the human are the main characters. Gaster is the one doing the adopting, and the human is the one being adopted.
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.
At first, Sans would probably be a bit shocked, but then he'd turn on his laid - back, sarcastic attitude. He might make jokes at Gaster's expense, which could either annoy Gaster or make him respect Sans more. If Gaster tries to harm him, Sans could use his shortcuts to dodge attacks and try to find a way to reverse the situation. He'd also likely be thinking about how this affects his friends in the Underground, especially Papyrus, and try to find a way back to them.