Papyrus

Papyrus is one of the two skeleton brothers, and is a major character in the story. He wants to catch a human so that he can become a member of the Royal Guard.

Biography
The player first meets Papyrus after exiting the ruins. Papyrus then challenges the player to a number of puzzles, and then dates you. While dating, Papyrus realizes that your overwhelming love for him is not mutual, and dumps you. He gives you his phone number so the two of you can still talk throughout the rest of the game.

You learn that a flower has been speaking with Papyrus.

While sparing Undyne (and by sparing, I mean running away while she is trying to kill you) Papyrus calls you to tell you he thinks you and Undyne would make good friends. After this, you can stop by Undyne's house to find Papyrus waiting for you. He tries to act as a wingman, and jumps out the window.

Personality
Papyrus is a loud skeleton who presents a confident, charismatic image of himself. He tends to work hard, and despite his brash personality, he is a very kind skeleton at heart.

He really likes Spaghetti and cooks it in his spare time.

Attacks
He uses bones. Also he has a really cool special attack. Well no. He does a really cool attack instead of his special attack because a dog steals his special attack.

His "blue attack" turns you blue, which gives the element of gravity to the battle, and along with moving around to dodge attacks, you also have to jump.

The Player
Despite wanting to capture you, Papyrus still cares about you, and eventually ends up dating you if you pick the pacifist route. He eventually, however, turns you down, as he realizes he does not feel the same way about you. He does genuinely care about you, though, as shown through keeping you out of danger, and worrying about your well-being when you escape his shed (if he captures you) because you didn't let him know that you were escaping. You remain friends throughout the game.

Sans
Sans is Papyrus's brother, and though he often yells at Sans to stop being so lazy, the two of them care about each other a lot.

Undyne
Papyrus and Undyne are good friends. Being the head of the Royal Guard, Undyne took Papyrus under his wing to train him, however instead of giving him fighting lessons, she gave him cooking lessons, because she believed he was too nice to join the royal guard. Still, Papyrus continues to try his best to capture a human so Undyne will let him join the royal guard.

Flowey
In an optional conversation with Sans, it is implied that Papyrus has encountered Flowey, and that he receives flattery, advice, encouragement and predictions from Flowey.

Trivia

 * He is named after the font he speaks in, Papyrus.
 * Papyrus and Sans were inspired by the webcomic Helvetica, which features a skeleton named after a font.