Papyrus

Papyrus is the brother of Sans and one of the main characters in Underfell.

History
"You know; with a careless act of heroism like this, I'd punish you severely. However, I am in need of more royal guards."

- Asgore

At some point in the past, Asgore was about to execute Sans by crushing his head for unknown reasons. Papyrus was present at the execution where Sans apologized to him. But before Asgore could carry out the task, Papyrus selflessly jumped in to save his brother's life.

Impressed by Papyrus's speed and bravery, Asgore offered him a place in the Royal Guard in exchange for Sans' life being spared. Papyrus accepted the offer and became a member of the Royal Guard. Asgore declared that an act of defiance would not go unpunished and scraped his fingers across Papyrus's right eye socket, giving him his scar. Sans attempted to attack Asgore in anger for hurting his brother but was stopped by Papyrus, who believed that if Sans could have fought Asgore before he stepped in, then what was his sacrifice for?

Appearance
Papyrus is a tall skeleton with semi-closed eyes, has a scar (Shown on a ton of FanArt) and has sharp teeth. He wears a red cape, a pointed black battle body with a golden symbol on the left, long red gloves, black trousers with a red wrestle mania belt and red heels with 3 black stripes.

Papyrus shares many physical similarities to his Undertale counterpart. He is about three inches taller, at 6' 3", with good posture and bleached white bones. Has sharper teeth. Other than that, he looks like a relatively normal skeleton.

His battle body consists of a faded red and black color scheme, with broad, spiked shoulder armor, red gloves, and black tight pants. His red scarf is the highlight of his armor, and almost acts as a cape when worn, as it drags behind him when he walks.

Personality
Papyrus loves evil puns, but he hides this very well. He, like Sans, tries to be cool and collect. He doesn't laugh, but snorts. He also "HMPH"s and sometimes goes "MWAH HAW HAW HAW!".

He cares for Sans. He also cooks lasagna instead of spaghetti. And he gloats a lot for no reason, he can be awkwardly supportive.

Sans (Brother)
Sans and Papyrus try real hard to be the 'mature/cool brother' of the two. So there's a lot of them fighting (not in a violent way) or being sarcastic to each other, minding their own business. They don't hate each other at all. In fact, they really care for each other. They basically both have an "ugh, fine" kind of relationship, according to what Underfella said.

Undyne (Partner)
Undyne is close to Papyrus, because they spare with each other.

Frisk
(Note this is speculation as Underfell does not have a strict "canon" except their designs.)

Asgore (Boss)
Asgore was one of the people responsible for giving him his scar.

Trivia

 * His boots were given to him by Alphys.
 * He made his belt after beating Undyne.
 * He does not laugh, nor go "NYEH," instead snorting or going “MWAH HAW HAW HAW."