I don't own Undertale or Renegade. Undertale is owned by Toby Fox and Renegade is owned by SharaX Official.
Wow, maybe 'With Just a Toy Piano' should be based off of all the SharaX songs on YouTube...
This is NOT canon, but here's a picture I made while listening to Renegade.
NO THIS ISN'T CANON AND PROBABLY WILL NEVER BE
Feel free to use this to make your own spin-off though.
JUST CREDIT ME BECAUSE I WANT CREDIT FOR THE AU
And while we're at it, let's look at a random and slightly creepy picture I made while experimenting with a feature on Sketchbook...
It's nothing, but it could also be an eye...