Papryrus cooks Mario spaghetti.
As Mario is walking, Papyrus walks in, using a fake dance that is sexy enough to paralyse a human, but is just a joke by Sans. After learning that the dance was fake, he asks a question as a puzzle: 1+1. Mario can't figure it out and is captured. After Papyrus learns that Mario loves spaghetti-lover, he tries to save him from the police.
After Mario pokes Sans eye, Papyrus praises him, followed by a short while of dialogue from Undyne and Asgore. When mario is shown the exit, Papyrus chooses to be the castles cook.
Papyrus has yet to be depicted in another episode, but, as him and Mario go to the castle, it can be assumed he is there.