It's a fan - made concept where the worlds or characters of Underswap and Undertale interact. It often features unique storylines that combine the different character traits and settings from both.
There's a fanfiction named 'Grillby's Sanctuary'. In this story, Underswap Sans stumbles upon Grillby's place and what follows is a story of discovery and connection. The author does a great job of portraying the unique charm of both characters. It shows how Sans, with his laid - back attitude, can find a sense of peace and friendship in Grillby's presence. Also, some fan - made websites and forums are great places to find more Underswap Sans x Grillby fanfictions.
One common theme is redemption. The Underswap characters might try to help the abused reader find a way to heal and move forward. Another theme could be friendship. Despite the difficult situation, new bonds are formed between the reader and the Underswap characters.
One popular one is 'The Swap - Tale Adventure' which has great character interactions. Another is 'Underswap in Undertale's World' which really delves into how the Underswap characters adapt to the Undertale setting.
The relationship could start with suspicion. Frisk, coming from their own world, might not trust this new Chara right away. But as they spend time together, they could find common ground. For instance, if they both have a love for the unique monsters in their worlds. This could gradually lead to a friendship where they rely on each other.
Well, Frisk could be cautious at first. Since Chara in Underswap is different, Frisk might be on guard. However, as they get to know each other, they could become friends. For example, they might share stories about their friends in their respective worlds. Frisk could talk about Sans and Papyrus, while Underswap Chara could talk about their own versions of the characters. Eventually, they could team up to face some challenges in the Underswap world.
An emotionless girl reader may seem indifferent to the themes in an Underswap fanfiction at first. But the unique themes that often come with the Underswap concept, such as role - reversals and alternate universes, could start to make her think more deeply. She might not feel excited or intrigued in the traditional sense, but she could start to engage with the themes on a cognitive level. This could lead to a sort of internal exploration where she begins to compare the themes in the fanfiction to her own experiences (even if she doesn't have strong emotional ones). And who knows, this might be the start of her developing some form of emotional response in the long run.
One popular one might be 'A Tale of Two Skeletons'. It delves deep into the relationship between undertale sans and underswap papyrus, exploring their different personalities and how they interact in a unique AU setting.
I'm not sure about specific 'abused reader meets underswap fanfiction' works off the top of my head. But you can try searching on fanfiction platforms like Archive of Our Own. They have a large collection of fanfictions and you might be able to find what you're looking for by using those keywords in the search bar.