Papyrus

Papyrus is Sans's brother and the last recruit of the Underground's Royal Guard.

Appearance
Papyrus is an Overlander skeleton who is relatively taller and more slimmer than his older brother, Sans. He wears a red scarf, a chest plate with yellow trim with a golden symbol on his left chest, grey clothing that covers his arms, hips, and legs, red gloves with yellow trim, a blue brief with yellow trim, and red boots with black stripes.

Biography
Papyrus never knew his parents, as they both "died" when he was just a baby. His only family was his older brother, Sans.

At some point, Papyrus decided to join the Underground's Royal Guard. It is known that he stayed a whole night at Undyne's doorstep, just to ask her to join the Royal Guard. Undyne agreed to train him, but, since Papyrus had a pure heart and wouldn't be able to kill anyone, she started to teach him how to cook. None of them, however, was good at that.

After the first Genesis Wave, it turns out that Papyrus befriended Flowey, only to be betrayed. Flowey, however, always paid for this betrayal, as Sans defeated Flowey every single time Flowey betrayed Papyrus.

After the second Genesis Wave, Frisk fell in the Underground. Papyrus was one of the first monsters to befriend them on the Pacifist Runs. Even on the Genocide Runs, Papyrus believed Frisk was not absolutely evil. However, Papyrus never knew about Frisk's "All or nothing" philosophy, nor that Flowey was actually Asriel Dreemurr, the lost prince of the Underground. After a few runs, however, he started to become suspicious, as Sans started to be secretive towards him.

After the Super Genesis Wave, his history became mostly unchanged.

Personality
Papyrus has a pure heart and wouldn't be able to hurt anyone. His pure heart allows him to see good in evil, as "EVERYBODY CAN BE A GREAT PERSON IF THEY TRY".

Papyrus is somewhat of a narcissist. This, however, only influences his pure heart by claiming that one befriending him will make that person as great as him. Evidence is Frisk's Genocide Route, where Papyrus offers to be Frisk's friend right away, and claims that sparing him will turn their life right around. This belief of Papyrus that he can help his friends be as great as him is partially true, as sparing Papyrus after he offers to be Frisk's friend aborts the Genocide Route.

Papyrus's pure heart makes him very caring, as seen in his relationship with Sans. Papyrus often scolds Sans for his laziness (as Sans always sleeps when he's not at work) and cleans up after him. This is also shown after a reset, as Sans is down because of it, and Papyrus feels there is something wrong with Sans.

Papyrus's other quality is his perseverance. Once, he stayed up at Undyne's door an whole night, just to ask her to join the Royal Guard.

Powers and abilities
Contrary to Undyne's belief, Papyrus can protect himself. In battle, he uses a bone and Gaster Blasters to block enemy attacks and often prevent his foes from moving with his "blue attack". With this attack, Papyrus basically stabs his foes with blue bones, which hurt if the foe moves.

Papyrus has a "special attack" which involves stabbing his foes with giant regular bones.

Trivia

 * Contrary to popular belief, Papyrus's favorite food is oatmeal with dinosaur eggs and not spaghetti. He still, however, likes spaghetti, especially making it for his friends. But he isn't good at it, even if he will eventually become good at it.
 * Contrary to popular belief, Papyrus doesn't hates Sans's puns, as he makes puns himself.