Well, there's 'Little Brother Sans: A New Beginning'. This fanfiction delves into how Sans' little brother copes in the unique world they live in. It has great character development and a plot that keeps you hooked from start to finish. The author does an amazing job of creating a believable backstory for the little brother character.
I also like 'When Sans' Little Brother Met Frisk'. In this fanfiction, Sans' little brother has an encounter with Frisk, and it leads to a series of events that change the dynamics of the story world. It's full of emotions, from friendship to fear, and the way the author writes the interactions is really engaging.
One popular 'big brother and little brother fanfiction' is 'The Bond Beyond Blood'. It shows a really heartwarming relationship between the two brothers. They go through various challenges together, like dealing with school bullies and family problems. It's a great read if you like stories that focus on the strong bond between siblings.
One popular sonic little brother fanfiction is 'The Adventures of Sonic's Little Brother'. It has an interesting plot where Sonic's little brother goes on his own quests, facing unique challenges different from Sonic's. It shows his growth and how he carves his own identity in the Sonic universe.
One great 'Harry is a little brother' fanfiction could be 'The Younger Potter'. It shows Harry in a different light as a little brother, with his relationships with his family members explored in depth. The author does a wonderful job of creating a believable family dynamic.
I also like 'Sephiroth and His Little Brother: Unbreakable Ties'. This fanfiction focuses on the emotional connection between the two. It starts with the little brother looking up to Sephiroth and as the story progresses, they face numerous trials that test their bond. It's really interesting to see how their relationship evolves through different events and how they support each other in times of need.
A lesser - known but quite interesting one is 'Ron's Little Brother Perspective'. It gives a fresh take on the events in the original story from Ron's point of view as the little brother. It makes you see his actions and reactions in a whole new light, especially in relation to his family and friends.
Well, I really like 'Little Brother Castiel's Hidden Powers'. In this fanfiction, Castiel discovers some unique powers he has as the little brother. It's full of action and mystery. Also, 'Castiel: The Little Brother's Bond' is a heartwarming story about the special bond he forms with his brothers. It shows how his role as the little brother shapes the family dynamics. You should check them out if you're into Castiel fanfiction.
One popular 'big brother x little brother fanfiction' is 'The Bond of Brothers'. It focuses on their growing relationship through various challenges. Another one could be 'Brotherly Love in the Shadows' which shows how they support each other in a fictional world filled with magic and mystery.
The relationships are a big part. Seeing how Sans interacts with his little brother, whether it's protective or playful, adds depth to the story. It's like exploring a new side of Sans' character that we might not see in the original game.
I'm not sure of specific 'lust sans x fell sans fanfiction' titles. But you can try searching on fanfiction websites like Archive of Our Own. They usually have a wide range of fanfictions and you might be able to find some related to these characters there.
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.