"don't smoke, kid. it's real bad. us skeletons have no lungs so we do what we want, y'know?"
Papyrus bears a close resemblance to Undertale Sans in many ways. His font is still Papyrus, but dominantly lowercase. He wears a red-orange sweater and brown shorts, and he is often seen smoking. He is extremely lazy and annoys Sans with bad puns, but both brothers care a lot about each other. Papyrus, much like Undertale Sans, can seemingly teleport from place to place and can be dead serious at times. Papyrus loves honey in the same way Undertale Sans loves ketchup. Instead of going to Grillby's periodically (as Undertale Sans so often does) he goes to Muffet's, a sweet shop full of baked goods made by spiders, for spiders and of spiders. Like Undertale Sans over Papyrus' death, if his brother is killed, Papyrus will most likely disappear and stalk the human, before attempting to kill them in the genocide boss fight. In the genocide run, checking Papyrus will lead to the discovery of his extremely low stats (much like Undertale Sans). Papyrus have weapons that called Gaster-Blasters/
Prior to the game's events, Papyrus had been using the door to the Ruins to practice his knock knock jokes. However, instead of Toriel (in Undertale) Asgore was behind the door, and they became very good friends. Asgore asked Papyrus to promise to protect any human who comes through the door, which Papyrus obliges to. This is the only reason that he did not kill you on sight, prompting his eerie message- "You'd be dead by my hand".
Many details in the skeleton household are similar to Undertale (Papyrus's workshop in the basement, the broken machine, the locked room, etc.) However, on the hangout/date with Sans, he will encourage you to visit the recycling bin, and inspecting the TV will initiate a Napstabot episode.
As well, Papyrus and Chara are considered as Best Friends after first met, He does an 'Old whoopee cushion hand trick' When they first met, Papyrus always pranked Chara, Like the Hotdog, instead of a normal hotdog, its a water sausage.
Sans is the younger brother of Papyrus, just like Undertale Sans, Papyrus cares about Sans, and doesn't want anything bad to happen to him. They share the same relationship as normal Sans and normal papyrus, often cracking puns to annoy Sans.
Papyrus' and Asgore's Relationship are getting Closer, since they always share what they Like, They always make Bad puns, and Knock knock jokes, Making them both as Best Friends, Since Papyrus doesn't like making promises, He just try to keep Asgore's Promise to keep Chara Safe.
Papyrus and Temmie also Hate each other, Papyrus also cause 'Temmie's Fair share of Resets' Since Temmie mentions Papyrus, calling him 'Smoking Smiley Trashbag'. Temmie and Papyrus always fight each other, since Papyrus always win after the argument, or after the fight.