Papyrus

 (/pəˈpaɪɹəs/, pa-PIE-rus), known as COOLSKELETON95 on UnderNet, is the younger brother of Sans and a major character in Undertale. He wants to catch a human so that he can become a member of the Royal Guard.

Appearance
Papyrus is a tall, perhaps anatomically inaccurate skeleton with a skull shaped in a more straight and geometrical structure (in contrast to his brother's more rounded skull). His mouth is in a smile shape most of the time and his eyes are pupil-less, resembling vertical slits with his expressions being formed mostly by his skeletal pseudo-brows.

He wears a custom-made costume known as his "battle body", which is made up of a white torso piece with various golden trims (and embroidered with a symbol that very heavily resembles that of the Starman from the Mother series), a rough red scarf or cloth around his neck, red gloves (trimmed with gold), blue briefs with a golden belt, and long red boots.

Personality
Papyrus is a loud and flamboyant 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 is extremely optimistic and innocent, as shown on a Genocide run when he continues to believe the protagonist is good at heart, even as the protagonist attacks and ultimately kills him.

Papyrus is occasionally rather oblivious and nonobservant, such as when he tries to rub different kinds of creams and "sauces" behind his ears, only to realize that he doesn't have any ears. He can be cunning at times, especially when he uses reverse psychology to trick Undyne into making friends with the protagonist.

For all of his skeleton faults, Papyrus seems to match this with how overwhelmingly determined he is, a feature that made Undyne take notice of him when he waited and begged her from midnight to morning for her to accept him into "royal guard training".

He really likes spaghetti and cooks it in his spare time, though many characters seem to think that he's really not very good at it (the protagonist describing the taste as "indescribable"). Sans says that ever since he started taking lessons that his culinary talents have improved greatly and that in a year, his food might even be "edible". He also has a love for puzzles, as shown in his dialogue and the numerous amount of puzzles he prepares whilst the protagonist approaches Snowdin.

Main Story
Sometime before the events of Undertale, Papyrus and his brother showed up one day in Snowdin and asserted themselves. Sometime after that, Papyrus became friends with Undyne and began training with her.

Neutral Route
Papyrus makes his first appearance in Snowdin Forest, where he proclaims to Sans that he will capture a human, unbeknownst to the protagonist hiding behind a conveniently shaped lamp, and berates Sans for not putting in his full effort to prepare his puzzles. Papyrus meets the protagonist for the first time face-to-face further on into the forest, where he is at first distracted by a rock behind the human, but quickly notices the human standing right in front of him.

Papyrus continues to weakly antagonize the protagonist with puzzle after puzzle, but quickly begins to warm up to them, and almost refuses to fight them when they finally meet him alone at the end of Snowdin. He shakes off the notion, however, and initiates an encounter. Papyrus never actually kills the protagonist, and, if they are reduced to 1 HP, instead captures them and places them within his shed, from which they can easily escape.

Ultimately deciding that this human is friendly, Papyrus lets them continue into Waterfall, giving them advice on how to exit the underground and also offering either a hangout or a date back at their house, depending on whether they insulted or flirted with him, respectively.

Returning to Papyrus' home after this will initiate the hangout or date, where Papyrus will dress in his secret style, and hide a special gift of spaghetti under his hat for the protagonist. Ultimately, however, Papyrus decides that the protagonist cares too much about Papyrus for their own good, and sends them back on their way with his phone number, which can be called at any time later in the game to hear Papyrus' opinions and thoughts on various areas of the underground.

When the protagonist makes their way into Waterfall, Papyrus is seen attempting to sway Undyne from killing them; Undyne refuses to yield, however, and Papyrus finds himself obligated to help her. He contacts the protagonist's phone and asks them to confirm the type of equipment they're currently wearing. Shortly after the call, Undyne finds and ambushes the protagonist. After the protagonist escapes, Papyrus rings them up again and explains that he used the information to try to deceive Undyne. The way in which Papyrus's lie backfired depends on whether the protagonist answered him honestly or changed their clothing afterward.

During the protagonist's ultimate confrontation with Undyne, Papyrus calls yet again and suggests that the three of them hang out; if the protagonist gives Undyne water in Hotland, Papyrus will make good on this suggestion and be waiting at Undyne's home for the protagonist to initiate the hangout. He flees from the premises early on, however, forcing Undyne and the protagonist to become friends one-on-one. After this succeeds, Papyrus invites Undyne to stay at his house (on account of the fire that now lives there).

True Pacifist Route
Befriending Papyrus is necessary to finish the True Pacifist Route. He is present later on when Undyne gives the protagonist the letter that initiates Alphys's date, and appears finally during the ending of the Pacifist Route, where he is one of the monster friends whose souls Asriel Dreemurr captures, but is ultimately saved along with all monsterkind.

In the interactive epilogue, Papyrus discovers that there is no need for the Royal Guard anymore, and proclaims that this is " THE WORST POSSIBLE ENDING ".

In the credits it appears many of Papyrus's dreams have come true: he is shown driving a red car along a highway, something he has always wanted to do, and later on, Asgore is shown trimming a hedge in the shape of Papyrus's face, something that Papyrus wished would happen once he became a famous royal guard.

Genocide Route
In the Genocide Route, Papyrus pulls much of the same antics that he does in a Neutral/Pacifist route, except often cites the protagonist's unwillingness to complete his puzzles, describing it as "weird" and rationalizing it as "culture shock". He remains oblivious to the protagonist's actual personality until their battle, where he sees their killing intent and instantly spares them, wishing to guide the protagonist on a better path and be friends.

Should the protagonist choose to kill him, he states he still believes in the protagonist and thinks that they can be a better person. If they choose to spare him, then Papyrus is relieved that they "didn't do a violence", and says that he was secretly terrified of the protagonist. From that point on, the protagonist may choose to "hang out" with Papyrus, which acts similar to dating.

In Battle

 * See /In Battle

Frisk
Despite wanting to capture the protagonist, Papyrus still cares about them, and eventually ends up dating/hanging out with them if a Pacifist Route is taken. He eventually, however, turns the protagonist down if they choose to date, as he realizes he does not feel the same way about them.

He does genuinely care about the protagonist, as shown through keeping them out of danger, and worrying about their well-being when they escape his shed (if he captures them) because the protagonist didn't let him know that they were escaping. The protagonist remains friends with him throughout the game, and gains the ability to call him on the cellphone almost anywhere.

If Genocide Route is taken, in the battle with Papyrus, he instantly spares the protagonist and wishes to guide them on a better path and be friends with them. Even if the protagonist murders him in this route, he still believes that there is good in them and still wants to be friends.

If he is allowed to "win" in battle, he simply captures the protagonist and puts them in the shed, and asks them not to escape. Each time they escape (and allow him to win again) this escalates until Papyrus just gives them the option of not being captured at all.

Sans
Sans is Papyrus's brother, and though he often yells at Sans to stop being so lazy and he detests the many skeleton puns dropped throughout the game (especially Sans's), the two of them care about each other a lot. Sans refers to Papyrus as "cool". Papyrus often cleans up after Sans and states that Sans is lucky to have such a cool guy taking care of him. He was also the one to convince Sans to get a job as a sentry.

Sans cares deeply for Papyrus, a fact made especially evident should the protagonist decide to kill Papyrus. As the protagonist is being judged at the end of the Neutral Route, if the protagonist has killed Papyrus, Sans asks whether it's the protagonist's responsibility to do the right thing with their ability to SAVE. Should they say no, Sans denounces them as a "dirty brother killer." In a Genocide run, should Sans be slain by the protagonist, he calls out to the long-dead Papyrus with his dying breath, masking his despair with his usual carefree persona.

Additionally, during an encounter with Shyren, the protagonist can hum with it to start a concert. If Papyrus is alive, Sans will be selling tickets to the concert made of toilet paper. If Papyrus is dead, regardless of a Genocide run or not, instead "a hooded figure watches the commotion from afar." It is heavily implied the figure is Sans.

Undyne
Papyrus and Undyne are good friends. Being the head of the Royal Guard, Undyne took Papyrus under her 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. He believes that she and the protagonist can truly get along, even offering to be their "wingman" for their friendship.

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, probably to Flowey's benefit. Flowey also told Papyrus to bring him and Undyne, Asgore, Sans, and Alphys, to bid the protagonist farewell. Flowey actually wanted them to gather in order to harvest their Souls to regain his true form.

Flowey mentions in one of his Neutral Route endings that he used his SAVE ability to interact with Papyrus numerous times. He says that Papyrus had started the "Flowey Fan Club" in several different timelines. Flowey says that he found Papyrus as one of the better characters to mess around with and took a long time to get bored of him.

Name
Papyrus's name alludes the typeface in which he speaks in, Papyrus. This is a reference to Helvetica, which is a webcomic about a skeleton named after a font. In the Graphic Design field, Papyrus and Comic Sans are both widely considered to be unoriginal, mediocre, poorly designed, informal and overused fonts.

When attempting to name the fallen child "Papyru", the response becomes "I'LL ALLOW IT!!!"; as the character limit in the naming screen prevents Papyrus's full name to be entered.

Trivia

 * He is the only character in the entire game whose dialogue doesn't begin with an asterisk.
 * While hanging out with Undyne, she mentions that Papyrus is "actually pretty tough", but doesn't have the heart to be a warrior, which is why she chose to teach him cooking instead. This is reinforced by the fact that the "regular attack" that he was forced to use after the Annoying Dog stole his special attack is actually fairly impressive in spite of not being his strongest attack. Also, he is intentionally holding back during the fight because he wants to capture, not kill, the protagonist.
 * Attempting to leave the electricity maze in Snowdin Forest will cause Papyrus to tell the protagonist not to be rude since he made the puzzle just for them. Backing away again causes Papyrus to ask if the protagonist treats their mother the same way when she makes them puzzle. Afterwards, he will just respond with " HUMANS... ".
 * Doing this again during Sans's Monster Kidz Word Search puzzle will cause Papyrus to tell Sans that the human is escaping since he made the puzzle too hard.
 * During the fight with Papyrus in a Neutral or True Pacifist run, there is a dialogue where Papyrus mentions having a hedge trimmed in the shape of his smile by the king, Asgore. Later, during the True Pacifist Ending Credits, this is shown to come true, as he trims a hedge shaped like Papyrus's head in front of Toriel's school.
 * The same happens with Papyrus's dreams of riding a car on the surface; a scene in which he does exactly that appears earlier in the True Pacifist Ending Credits.
 * During Papyrus's "special attack", a long array of bones with one large bone approaches from the right of the bullet board. If the player jumps, lets go of the up button, and then jumps again, the heart will remain on the ceiling of the bullet board once this attack ends.
 * There is a glitch where Papyrus will speak without using his font. Before the befriending event with Undyne, if the protagonist confirms the hangout from either side of Papyrus, speaks to the Dummy, then walks up to Papyrus from behind, this glitch will occur. Papyrus will speak in his font after Undyne answers the door, however.
 * When the protagonist visits Papyrus's house for the first time, right before the date/hangout, continuously walking in and out of Papyrus's kitchen at a rapid pace causes him to dash quickly to the left and to the right (as Papyrus does follow the protagonist to the kitchen when they enter it, then goes back to where he originally was as they exit it). Eventually, a tinkling sound will be heard every time the protagonist switches rooms, leading to a different 'completion' sound. If the protagonist talks to Papyrus after that, he'll mention he can't feel his legs, which must mean he is a great host.
 * Upon killing Papyrus by cutting off his head, he says "Alas, poor Papyrus!" This is likely a reference to Shakespeare's Hamlet, of the famous scene where Hamlet talks to the skull and says "Alas, poor Yorick!"