Ink!Sans is the deuteragonist in Underverse and the protector of all the AUs. He originally made a truce with Error!Sans to never create another AU again so that he wouldn't destroy the other AUs. Later on, he meets XGaster in XTale and gracefully shows him the multiverse; he would later on give Ink his half soul within a white/purple vial.

In the long run, Ink!Sans is generally optimistic, has a sense of kindness, loves making art, and can get too excited even to the point of throwing up ink.