One interesting fanfic could be 'A Shared Soul'. It delves deep into how Frisk and Chara's relationship develops in a post - pacifist world. It shows how they understand each other on a deeper level and face new challenges together.
You can start by searching on fanfic platforms like Archive of Our Own. Just type in 'Undertale Frisk x Chara' in the search bar, and you'll get a list of relevant fanfics. Then you can sort them by popularity or rating to find the good ones.
Friendship is a very common theme. These fanfics often show how Chara and Frisk become friends and rely on each other. Another theme is adventure. They usually go on adventures in the Underground together, facing various monsters and challenges.
One popular fanfic in this category could be 'A New Beginning'. It explores the relationship between female Chara and female Frisk in a very heartwarming way. It focuses on their adventures together in the Underground and how they grow closer as friends and more.
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.
Frisk and Chara have a complex relationship already in Undertale. When Error enters the picture, it gets even more interesting. Frisk might be the mediator between Chara and Error. Chara could be hostile towards Error initially, seeing him as a threat to their own existence or plans. Error would likely be dismissive of both of them at first, thinking they are just insignificant parts of a world he might want to destroy.
Well, one possibility is that there would be a lot of confusion. Frisk, being the kind-hearted protagonist, might try to reason with Error. Chara, on the other hand, could be more unpredictable. Error might see them as glitches in the fabric of his world - or whatever strange view he has. Maybe he'd try to destroy them at first, but Frisk's determination could change his mind.
One great fanfic is 'A New Beginning'. It beautifully explores the relationship between Frisk and Flowey. It starts with Frisk finding a more vulnerable side of Flowey, and as the story progresses, they form an unlikely bond that challenges the norms of the game world. The author does an amazing job of delving into their characters and making their interactions feel genuine.
I really liked 'The Unlikely Bond'. In this fanfic, Papyrus and Chara start off as enemies but gradually come to understand each other. The story has a lot of emotional depth, with Papyrus trying to see the good in Chara and Chara learning to open up. It's full of heartwarming moments and some really cool plot twists that keep you hooked.
I'm not very familiar with frisk x chara futa fan fictions specifically, but generally in fan fictions about characters from a game like Undertale, themes could include friendship, adventure, and self - discovery. But this is just speculation as I haven't studied these particular fan fictions in depth.