Sans

Sans ( [sænz], SANZ) is the older brother of Papyrus, and a major character in ''Undertale. ''He first appears in the forest outside Snowdin Town. He is either a supporting character or a heroic antagonist.

Appearance
Sans is a short and big-boned skeleton, wearing a hoodie or simple jacket, unzipped at all times, with a white shirt, black shorts and sneakers according to his Steam trading card (can be also interpreted as slippers as seen in the official merchandise.)

He is seen with a grin at all times, and only moves the corners of his mouth at certain scenes. He has white pupils, which tend to disappear when he is serious. A bright, flashing iris appears in his left eye socket during the battle against him, as well. This eye starts off merely glowing, but as he utilizes his time warping powers, it starts to flash vividly.

Abilities
He is shown to be able to move exceedingly quickly and/or teleport through his frequent use of "shortcuts", as he calls them. In battle, he shoots what appear to be a kind of beam using "Gaster blasters", a device resembling a goat or dragon skull. These also bear similarities to the DT Extraction Machine found in the True Lab, Gyftrot's head, and Asriel's first form's head.

He has obtained the knowledge of multiple timelines and the SAVE function, presumably through his scientific research. However, it appears he does not actually retain knowledge when the player loads a SAVE, and cannot use the SAVE function himself. It may be that his awareness of the situation and his innate perception allows him to recognize when the player is behaving unusually.

Sans seems to know if the player has achieved an impossible ending in the Neutral Route's phone call and will call them a dirty hacker. Given that this also counts as an error handling message, he is aware of when the game's code suffers bugs as well.

Personality
Sans is shown to be very laid-back, sleeping on the job as often as he takes breaks. He enjoys making bad puns relating to skeletons, to the annoyance of his brother. He is kind and reassuring, but becomes eerily serious at abrupt moments (particularly when angry.)

He is also very observant, and his lines and actions change more in relation to the player's choices than any other character. He knows the number of times he had defeated the player (in Genocide Route.) He hates to make promises, although he promised Toriel he would protect the player.

His laziness is noted during the final fight in the genocide route - he is unsure if being somewhat aware of the timeline resetting has broken his spirit, knowing that everything he does will mean nothing... or if he's just using it as an excuse to slack off.

Although he does not outwardly show it, Sans exhibits nihilistic traits, evidenced by his lack of motivation and feelings of hopelessness to the point where he is willing to give up, which was misinterpreted by many others as being lazy in general. His nihilism stems from his knowledge of multiple timelines and the SAVE ability, knowing that even if monsters escape the Underground, the timeline will be reset and the monsters will just end up back in the Underground without retaining their memories. Sans is also fully aware that his own life is already forfeit.

Neutral Route
Sans first meets the protagonist after they walk out of the Ruins into Snowdin Forest. They are pursued by Sans, who first appears as a silhouette. After introducing himself, he explains that despite being a sentry, he has no interest in capturing humans, although his brother, Papyrus, does. He then hides the protagonist from his brother behind a conveniently shaped lamp, while he and Papyrus have a heated discussion of Sans's laziness and the importance of puzzles. Sans appears multiple times throughout Snowdin Forest, usually alongside Papyrus, observing and commentating on the puzzles but not actively engaging in any japery, except for the word search.

Sans is absent in Snowdin Town, although he appears abruptly during the protagonist's date with Papyrus, sticking out of his room with a trombone. If the player kills Papyrus, Sans is absent throughout the rest of the game, until he resurfaces to give his judgement.

After entering Waterfall, Sans is found manning another sentry post, and asks if the protagonist wants to hang out with them. If the protagonist agrees, he takes them to Grillby's via a 'shortcut'. Sans is greeted warmly by the patrons of the diner, and proceeds to treat the protagonist to a burger or some fries. After some ketchup nonsense, a spotlight falls on him. Sans then tells the protagonist that Papyrus has mentioned a flower has been talking to him, and mistakenly believes that someone is tricking him with an Echo Flower, when in reality the flower in question is Flowey.

Sans is met again in Waterfall, and pranks the protagonist with a red-eye telescope.

The protagonist passes him sleeping at one of the sentry posts in Hotland when fleeing from Undyne. Once Undyne notices him sleeping, she becomes quite angry, causing her to stop to berate him.

Sans is also encountered later on in Hotland selling hot dogs. If the protagonist attempts to buy a hot dog with no room in the inventory, he will begin to place the hot dogs on their head. He will stack a maximum of 29.

Sans later runs across the protagonist outside of MTT Resort, where he offers them to grab a bite at its restaurant. If they agree, He will escort them through one of his 'shortcuts'. At the restaurant, Sans reveals he had befriended a woman with a similar affinity for puns, that resided on the other side of the entrance to the Ruins. He tells the protagonist that the woman made a request to which he promised to comply: to watch over and protect any human who came through the door. He states that if not for his promise, the protagonist would be "dead where [they] stand", which he dismisses as a joke shortly afterwards. He mentions how he's doing a good job at protecting the protagonist, though he will question it if they have died before. Before leaving, he tells the protagonist to take care of themselves, because there's someone who really cares about them.

Judgement
While passing through the final corridor, Sans encounters the protagonist one last time. He proceeds to judge them for the EXP earned throughout the game, revealing that EXP stands for "EXecution Points", and that LOVE stands for "Level Of ViolencE". His judgement is determined by the protagonist's actions throughout the game.
 * If the protagonist gained no EXP, Sans will begin to talk normally and will skip his judgement, telling the protagonist that they never gained any LOVE, and that they have always striven to do the right thing. He goes on to say how he appreciates the protagonist for having kindness in their heart, telling them that the Monsters' fate is in their hands; they can either let Asgore take the protagonist's soul for their freedom, or take Asgore's soul for the protagonist's escape. He tells the protagonist that he believes their determination will help them do the right thing. He then leaves.
 * If the protagonist resets from a save point after hearing his speech, Sans will take note that you've already heard this speech before and will give you a secret codeword. The protagonist must repeat this about two more times until Sans gives you the key to his room.
 * If the protagonist gained some EXP, Sans will give them a moment to think on their actions. After a moment, he will begin to talk normally, and will tell the protagonist that all that matters is that they were honest with themself.
 * If the protagonist spared Papyrus but killed other monsters, Sans tells the protagonist that it will be left up to the protagonist to decide what will happen. He then leaves.
 * If the player resets from a save point after hearing his speech, Sans judges the protagonist based on how high their LV is:
 * If the protagonist is at LV 1 (but has more than 0 EXP), Sans presumes that they killed someone just to see what he'd say about it. He says "wow. you're a pretty gross person, huh?"
 * If the protagonist is at LV 2, Sans says that it's pretty sad that the protagonist messed up the slightest amount, and that they probably didn't know what they were doing, but then says that he's kidding, stating: "who gets to LV 2 on accident? get outta here."
 * If the protagonist is at LV 3, Sans gives you a C+, and tells you that you can do better.
 * If the protagonist is above LV 3, Sans says that they probably killed some people on purpose, though maybe some of it was in self defense, and that he's not sure, as he wasn't watching.
 * If the protagonist is above LV 9, Sans says that doesn't mean that the player is 50% good, and questions "what can I say that will change the mind of a being like you...?"
 * If the protagonist is above LV 14, Sans will say that the protagonist is a "pretty bad person, " but that they could be worse, and that they "pretty much suck at being evil."
 * If the protagonist killed Papyrus, Sans goes on to tell the player that he suspects they have some sort of special power, and asks if they think it should be their responsibility to do the right thing. If the protagonist says "Yes," he then asks why they killed his brother. If the protagonist says "No," he says that he won't judge the protagonist for their viewpoint, but calls them a "dirty brother killer." Either way, he will leave after reminding the protagonist of Papyrus's death at their hands.

Endings
After the fight with Photoshop Flowey, Sans will call the protagonist, and inform them of the events that transpired after their departure. The content of this phone call varies depending on the protagonist's actions, and a list of the different endings which Sans can describe is found on the Neutral Route page.

True Pacifist Route
Sans appears during the cutscene that occurs after the protagonist initiates the battle with Asgore. Toriel recognizes his voice, and they meet face-to-face for the first time. Toriel recognizes Papyrus as his brother, saying that Sans has told her a lot about him. Sans, along with the protagonist's other friends, are bound by Flowey, yet still protect the protagonist against Flowey's attacks. However, Sans is absorbed by Flowey, along with the souls of all the other monsters.

During the battle against Asriel, Sans appears as one of the lost souls.

After defeating Asriel, Sans stands alongside the other main characters. If you talk to him, he says a certain remark depending on what, if anything, the protagonist said to Toriel at the beginning of the game. Sans also uses Toriel's phone to text for her a few times. After the protagonist is ready to leave, Sans exits the Underground and heads to the Surface along with the other monsters.

Papyrus runs off to introduce himself to the humans, and Sans says someone's got to keep him away from trouble, and runs off in the opposite direction presumably to use a "shortcut". In the credits, Sans is seeing riding a tricycle on a highway, while his brother races along in a car.

Genocide Route
Sans stalks and introduces himself to the protagonist as usual, and although he recognizes the protagonist as not being human, he tells them to keep pretending to be human as Papyrus has always wanted to see one. He goes along with Papyrus' japery, although he does not appear in the same places he does on regular routes. After the protagonist crosses the bridge, Sans warns them not to fight their brother, or else they'll "have a bad time." He then suddenly disappears, and is absent until the final corridor.

If the player aborts the Genocide Route by sparing Papyrus, Sans will reappear at the Waterfall sentry station, and tell the player he respects them for doing that. He will continue to appear as if on the Neutral Route, but will not take the player to Grillby's, since there's no one left in Snowdin Town.

In the final corridor, Sans asks the protagonist whether or not a person can change. Not expecting an answer, he continues and asks if they "wanna have a bad time? ", warning them to not take another step forward. After the protagonist continues forward, Sans then engages a fight against the protagonist, and apologizes to Toriel (who is absent) for breaking his promise to protect the protagonist.

After some short monologue, Sans begins a furious onslaught of attacks against the protagonist, while contemplating why he has not done much to prevent the protagonist's actions. After he finishes his speech, Sans offers to spare the protagonist, telling them that accepting will make his job a lot easier.

If the protagonist spares him, he tells them that he won't let the protagonist's work go to waste. He then kills them with an unavoidable attack, and asks them in the game over screen not to return if they really are a friend. If the protagonist does come back, Sans's second attempt to convince the protagonist to spare him is a little half-hearted, suggesting that he knows the protagonist has already fallen for it and is unlikely to do so a second time. When the protagonist attacks him, he says that means they never really were friends, and asks the protagonist not to tell other instances of Sans in other timelines.

If the protagonist does not spare Sans, then the fight continues, with Sans saying that it was "worth a try". Sans continues to assault the protagonist with further attacks, and the textbox proclaims that "The REAL battle begins." After the protagonist dodges all of his attacks, Sans, in a desperate attempt to kill the protagonist, repetitively slams the protagonist's soul against the walls of the battle box, although the protagonist survives this. Sans then uses his "special attack", which ends up being nothing (and thus never ends Sans's turn), as Sans hopes that if nothing happens, the protagonist will quit out of boredom or simply remain trapped forever. However, Sans eventually falls asleep, allowing the protagonist to push the box so that they can select the FIGHT option. Sans dodges the first attack, but the second attack (unprovoked by the protagonist) hits. He appears to bleed from his wound, though it's speculated that the "blood" is truly ketchup, since Sans is known to drink entire ketchup bottles. Sans reminds the protagonist that he warned them before getting up, and weakly walking off-screen. Sans's death grants the player enough EXP to reach LV 20.

In Battle

 * See Sans/In Battle

Frisk
Sans is the first monster the protagonist meets outside the Ruins. When he first meets the protagonist in Snowdin, Sans is friendly to them, regardless of the play style they are following. He plays jokes on them, using a "whoopee cushion in hand" trick when they first meet. He is able to tell whether the protagonist has experienced the events of the game before, and his attitude toward the protagonist changes drastically depending on how merciful, or otherwise, they are during the current playthrough. Sans only battles the protagonist at the end of a Genocide Route, where he believes that the existence of the world's timelines are in danger. In a Neutral (where you haven't killed Papyrus) or Pacifist Route, Sans enjoys joking around and messing with the protagonist (as shown when he pranks you with his telescope.) In the end, he does care about the protagonist's well-being, and he encourages them.

If the player dines with Sans in the MTT Resort, then Sans tells the protagonist that had he not promised to protect them, they would be "dead where they stand", implying that he would've killed them himself.

Papyrus
Sans cares for and admires his brother. He reads Papyrus bedtime stories, and even gifted him action figures. Nonetheless, he likes to prank and joke with his brother- which is typical of him. Sans is worried about other people taking advantage of Papyrus' innocence; he assumes that Papyrus talking about a flower talking to him is actually someone using an echo flower. If the player kills Papyrus, then Sans disappears until the final corridor, where (on a Neutral Run) he harshly judges the player for this. On various neutral endings, Sans is also afraid to tell Papyrus about the people you have killed, so he lies about them going on a vacation.

Toriel
Toriel and Sans are close friends, sharing a love of bad jokes. He never sees her in person until at the end of a True Pacifist run. While not being one to keep promises, in all runs except the Genocide Run Sans complies with her request to not harm any human that passed through the door exiting the ruins. Toriel keeps record of Sans's knock-knock jokes in her diary.

If the protagonist reaches him at the end of the Genocide Run, he indirectly apologizes to Toriel, as he is forced to break his promise in order to stop the player.

Flowey
Sans doesn't seem to know much about Flowey himself beyond that he's the talking flower that appears before Papyrus; although " talking flower " and " echo flower  " are in different colors when Sans mentions it and then claims somebody's using an echo flower for a prank.

On the other hand, Flowey states in one of the Neutral Route endings that he tried to experiment with Sans using his SAVE ability. However, Sans "caused more than [Flowey's] fair share of resets" as if Sans was just about the only thing capable of stopping him, much the same as it is for the player on the Genocide Route. Flowey also calls Sans a "Smiley Trashbag".

W. D. Gaster
There are a few things that hint a connection between Sans and W.D. Gaster. These include the blueprints found in his workshop and the fact that the sprites used for his animations are labeled "gasterblaster".

Trivia

 * His name alludes the typeface Comic Sans. This is a reference to Helvetica, a webcomic about a skeleton named after a font.
 * Comic Sans is named what it is because it is a sans-serif font designed for use as a comic book font. Sans serif fonts are fonts without serifs—the word sans being a French word meaning without. So ultimately, Sans' name means without.
 * Comic Sans and Papyrus are both highly controversial fonts. They are both widely used, but their detractors usually claim that they are overused, and often argue that they are ugly fonts to begin with.
 * In addition to speaking in Comic Sans, Sans himself is a comic and loves to make bad jokes. He is also a performer in MTT Resort's restaurant, hinting he may actually be a skilled comedian.
 * At certain points in the game, he will drop this behavior and use the normal font, 8-Bit Operator, instead. This is often when he's at his most serious. Additionally, his dialogue cannot be skipped and is not accompanied by his voice sounds.
 * When attempting to name the fallen human "Sans", the response becomes "nope." and prevents the name from being used.
 * Sans is shown wearing sneakers in his Steam Trading Card. However, he is shown wearing slippers on the official Undertale brand "Mercy" T-Shirt.
 * He, along with Papyrus, make a brief appearance at the end of Undertale Demo if the protagonist does a perfect pacifist playthough.
 * Sans may call the protagonist to ask if their fridge is running.
 * There is evidence that points that Sans comes from a scientific background.
 * This includes the quantum physics book, workshop, and broken machine found in his house.
 * Papyrus, in a phone call on the first floor of the Lab, will mention that he loves science fiction.
 * There is implication that Sans and Alphys know each other at the end of the True Pacifist Route.
 * He is one of the three characters who will try to convince the player to stop playing the game, the others being Flowey and the fallen human.
 * Sans loves to drink ketchup. If the protagonist declines ketchup on their fries on their rendez-vous at Grillby's, he drinks the bottle whole. Condiment bottles can also be seen in his sentry station in Snowdin Forest. This has led people to believe that he's 'bleeding' ketchup from his wounds at the end of his fight.
 * There is evidence to support the idea that Sans is left-handed.
 * Sans greets you with a handshake using his left hand.
 * At Grillby's he holds and drinks the ketchup bottle with his left hand.
 * When riding the tricycle in the True Pacifist Ending Credits, he uses his left hand to steer it, while keeping his right hand in his jacket.
 * He uses his left hand when using magic in his boss fight.
 * Despite being a skeleton, Sans's hand doesn't resemble a skeleton's. This could be, however, because he is wearing a glove, as his hometown's climate is cold.
 * After killing him in the Genocide Route, his death is not added to the protagonist's kill count.
 * Whenever Sans makes a joke or a pun at the beginning of the game and the comedy punchline rimshot sound plays, he will face the player sitting at the screen instead of the people who heard the pun/joke. This hints at the fact that he not only knows about the other timelines and the player's ability to SAVE and reset, but also that he is in a video game.
 * If the player has killed his brother in the previous run, when you talk to Sans in the bridge, he simply tells you sharply not to fight Papyrus. This means that, like most of the main characters, he also retains certain memories for the previous runs.