A common theme is the exploration of differences. Since they are from different universes, their personalities and ways of life are different. Fanfics often focus on how they deal with these differences.
The writing style is crucial. A good fanfic will have smooth and engaging prose. It won't be full of grammar and spelling mistakes. For this pairing specifically, the interactions between the two should be believable. They come from different 'universes' within the Undertale multiverse, so how they react to each other's differences and similarities can make or break the story. Also, a bit of humor or emotional depth can really enhance the fanfic.
There are some. You might want to check fanfiction.net as well. However, the quality can vary a lot. Some fanfictions focus more on the relationship development between Underswap Papyrus and Underfell Sans, while others might include more action or adventure elements related to their world.
One popular 'underswap sans x underfell papyrus fanfic' is 'A Tale of Two Skeletons'. It has an interesting plot that explores their unique relationship in a creative way. The author does a great job of portraying their personalities.
One common theme is the exploration of differences. Underfell sans and underswap papyrus are from different universes with distinct personalities. Fanfictions often focus on how they deal with these differences, like underfell sans's more aggressive nature compared to underswap papyrus's more positive and energetic self.
The clash of personalities. Underswap Papyrus is usually quite positive and energetic, while Underfell Sans has a more edgy and guarded nature. This contrast can lead to really engaging interactions in the fanfictions.
You can start by looking on fanfiction platforms like Archive of Our Own (AO3). There are often specific tags for Underswap and Underfell. Just search for 'Underswap Papyrus x Underfell Sans' in the search bar, and you'll likely find a variety of fanfics. Another option is to check out Tumblr. Some fans post links to their fanfics there or even post short fanfic snippets that might lead you to the full stories.
There's also 'Unexpected Encounters'. This fanfiction delves deep into how underfell sans and underswap papyrus might interact. It starts with a chance meeting and then unfolds into a story full of twists and turns. Their personalities are really brought to life in this one. It shows how they overcome differences and form a special connection.
There's also 'Swap Brothers' Bond'. This fanfic delves deep into the brotherly bond between Sans and Papyrus in the Underswap setting. It shows their daily adventures and how they support each other. The author does a great job of capturing the essence of their swapped selves, and it's full of humorous and touching scenes.
Characterization is key. A good fanfic should accurately portray the personalities of both Underswap Sans and Underfell Sans. Their unique traits, like Underswap Sans' more positive and friendly nature compared to Underfell Sans' tougher exterior, should be well - presented.