multifandomneutral
There are many headcanons in this story based on the Q and A where Toby Fox's original characters answer the question above. FANFIC EDITION! Maybe I can mess around with these official canons Toby claimed for them.
These are spoilers if you have NOT seen the QA yet, so go to undertaleqa.tumblr.com to see the dialogues before reading.
I suck at details, so there will mostly be dialogue. So, maybe there's a story like this, but better and more detailed.