originally drawn october 2023! october 3rd is ToriSans Day in the japanese UT fandom (though it seems like it might've been more of a thing a few years back, less so in recent years), and the official Toriel slippers had just been revealed around that time, so it was a fun excuse to draw Sans wearing them.

this is also referencing the merch advertisement intermission from the 5th anniversary concert, which shows Toriel wearing the megalovania shirt :] they support each other's merch!!