After going through the Ruins, you go to Snowdin and go behind a tree, seeing a lady with white hair, and a belly-shirt on planning traps for you, the human. She then notices you and smirks, then smiles a determined smile.

P: "I, the Great-Papy, shall stop you . . . with this puzzle of course!"

You eventually get past the puzzle but it makes Papy mad.

P: "Ugh! This is San's fault for not activating the trap! Well human, you have passed. You may continue on."