Sorry, I don't know. It's quite possible that the story of Undertale doesn't have a direct basis on any particular song. The music might have been crafted independently to fit the theme and mood of the game.
Some characters might be amused. For example, Sans would probably make some witty remarks about the fanfiction's plot twists. Papyrus, on the other hand, might be a bit confused at first but then get really excited if he finds a heroic role for himself in the fanfiction.
In a comical fanfiction, most of the characters would enjoy it to some extent. Sans and Papyrus would be great additions to a comical story, and they would probably laugh along with the funny parts. Frisk, depending on how they are portrayed in the fanfiction, would either be the source of the comedy or be reacting to the absurd situations. In a more serious and political - themed fanfiction about the Underground's society, Asgore and Toriel would have deep thoughts. They might discuss among themselves how the fanfiction's view of their leadership and the society they built compares to their own intentions.
It adds variety. The undertale fandom is huge and diverse, and frans lemon fanfiction offers a different take on the characters and their relationships. It gives fans who are interested in this particular pairing more content to enjoy.
To make Undertale comics, start by sketching out rough ideas. Pay attention to the game's art style and try to replicate it. Also, focus on capturing the emotions and expressions of the characters accurately.
The back story of Undertale involves a complex web of events and characters. It includes the history of the underground world and the reasons for the conflicts and struggles that take place.
First, you need to have a clear story idea for your comic. Then, sketch out the characters and scenes. Pay attention to the unique style of Undertale. Also, practice your drawing skills regularly.