First, understand the character of Underfell Sans. He's different from the normal Sans, more edgy and with a darker personality. Then, create an interesting scenario for the reader to interact with him. For example, a dangerous mission in the Underfell world.
Well, in writing a 'underfell sans x reader fanfiction', it's important to give the reader character some agency. They can't just be a passive figure. Also, use vivid descriptions to bring the Underfell world to life. Describe the dark alleys, the menacing creatures, and how Sans stands out in this world. And when it comes to their relationship, let it grow organically through shared experiences and challenges.
One great 'underfell sans x reader fanfiction' is 'A Dark Encounter'. It has a really interesting plot where the reader is thrown into the Underfell universe and has to navigate their relationship with Sans. The story is full of tension and character development.
Start by making a list of their distinct characteristics. Underfell Sans has a more angular appearance and a darker color palette, which can be reflected in his personality as being more cynical. Sans, on the other hand, is more approachable in appearance and personality. When writing their interactions, use these traits. Let their body language speak volumes. Underfell Sans might cross his arms and glare, while Sans slouches and gives a lazy grin. As the story progresses, these characteristics can be tweaked based on the events they experience. If they face a great loss together, it could make Underfell Sans more vulnerable and Sans more serious.
To write a great Undertale Underfell Sans x Fell Toriel fanfiction, you need to research the Underfell universe thoroughly. Know the rules, the power dynamics, and the overall atmosphere. When it comes to their relationship, start with small moments. Maybe Fell Sans brings Fell Toriel a small gift, like a flower from the dangerous parts of the Underground. This simple act can start to break the ice between them. As for the writing style, use vivid descriptions to bring the Underfell setting to life. Describe the dark corridors and the menacing monsters in the background as their relationship unfolds.
You can start by looking on Archive of Our Own (AO3). It has a large collection of fanfictions for various fandoms, including the Undertale AU crossovers like Underswap Sans x Underfell Sans. Another place could be Fanfiction.net, though the quality may vary more there. Additionally, Tumblr sometimes has users sharing or recommending such fanfictions in the Undertale fandom tags.
Frisk would be a likely candidate. Since Frisk is the main character in Undertale and has a very adaptable personality. They could approach Underfell Sans with an open mind and try to understand him.
One great 'underfell sans fanfiction' is 'A Darker Path'. It really delves into the darker aspects of Underfell Sans' character. Another good one could be 'Underfell Sans: Redemption'. It shows his journey towards a more positive change. And there's also 'The Underfell Sans Chronicles' which has a really interesting plot that keeps you hooked from start to finish.
Well, in the world of 'underfell sans abuse fanfiction', 'The Abyss Within' stands out. It has a very detailed description of the abuse scenario and how Sans endures it. This fanfiction is not for the faint - hearted as it gets quite intense. Additionally, 'Hope in Desolation' is also a great read. It shows the glimmer of hope in Sans's life despite the abuse he has faced, and the way the author develops the story is really engaging.
There's a really cool fanfic called 'FellSwap Encounters'. It delves deep into the relationship between underfell sans and underswap sans. It starts with a chance meeting and then shows how they gradually understand and support each other. The author does a great job of showing their different characteristics and how they complement one another.
There's also 'Sibling Rivalry Reimagined' which delves deep into how their personalities from their respective universes interact. It has some really interesting character development for both Sanses. It shows how their differences can lead to both conflict and unexpected understanding. The author does a great job of portraying their emotions and the way they communicate, which is quite different from the original game's interactions.
One popular 'baby underfell sans fanfiction' is 'The Tiny Terror'. It has an interesting take on the character in a baby form, with unique plot twists and character interactions.