Sans

Sans is the brother of Papyrus and a major character in Undertale. He first appears in the forest after the protagonist exits the Ruins. He serves as a supporting character in a Neutral and True Pacifist Route and as the final boss and heroic antagonist in a Genocide Route.

Appearance
Sans appears as a short skeleton with a dimpled smile, large eye sockets, and perfectly aligned teeth. He wears an unzipped blue hoodie, a white t-shirt/sweater, black shorts with white stripes, and a pair of sneakers/slippers.[1] He has white pupils that disappear when he is serious or angered. When Sans uses telekinesis, his left eye flashes light blue and yellow, the colors for patience and justice, and his right pupil disappears.

Trivia

 * 1) His Steam card shows him wearing sneakers and official merchandise shows him wearing slippers.
 * 2) ↑ "you can't understand how this feels. knowing that one day, without any warning... it's all going to be reset. look. i gave up trying to go back a long time ago. and getting to the surface doesn't really appeal anymore, either. 'cause even if we do... we'll just end up right back here, without any memory of it, right? to be blunt... it makes it kind of hard to give it my all. ... or is that just a poor excuse for being lazy...? hell if i know." – Sans
 * 3) ↑ "(It's a performance schedule.) (Comedians, dancers, Sans...)" – flavor text in the restaurant at MTT Resort.
 * 4) ↑ "A LAB??? MY BROTHER WOULD LOVE THAT! HE LOVES SCIENCE FICTION!! ESPECIALLY WHEN IT'S REAL." – Papyrus
 * 5) ↑ "i asked her what was up. then she told me something strange. 'if a human ever comes through this door... ...could you please, please promise something? watch over them, and protect them, will you not? now, i hate making promises. and this woman, i don't even know her name. but... someone who sincerely likes bad jokes... has an integrity you can't say 'no' to." – Sans
 * 6) ↑ 6.0 6.1 "WAIT, ALPHYS, I DIDN'T KNOW YOU KNEW SANS." – Papyrus, True Pacifist Ending.
 * 7) ↑ "HUH? MY BROTHER? OF COURSE HE HAS A TELESCOPE. SANS LOVES OUTER SPACE SCI-FI STUFF." – Papyrus
 * 8) ↑ "our reports showed a massive anomaly in the timespace continuum." – Sans
 * 9) ↑ The names of the sprites used for his attack animations begin with spr_gasterblaster_.
 * 10) ↑ "that look on your face while i was talking... you've already heard my spiel, haven't you? i suspected something like this. you're always acting like you know what's going to happen." – Sans
 * 11) ↑ "i'll be honest. i have no idea what happened for you to get here. this is actually some sort of error-handling message. so, if you're getting this ending... tell whoever made the game, okay? chances are, though... you're just a dirty hacker, aren't you? yeah, get outta here." – Sans's message to the protagonist if an impossible Neutral Route ending is achieved.
 * 12) ↑ "i'm actually supposed to be on watch for humans right now. but... y'know... i don't really care about capturing anybody. now my brother, papyrus... he's a human-hunting FANATIC." – Sans
 * 13) ↑ "IT'S BEEN EIGHT DAYS AND YOU STILL HAVEN'T... RECALIBRATED. YOUR. PUZZLES! ... YOU GET LAZIER AND LAZIER EVERY DAY!!!" – Papyrus
 * 14) ↑ "have you ever heard of a talking flower? ... so you know all about it. the echo flower. ... what about it? well, papyrus told me something interesting the other day. sometimes, when no one else is around, a flower appears and whispers things to him. flattery... advice... encouragement... ...predictions. weird, huh?" – Sans
 * 15) ↑ "FLOWERS...? DO ANY OF THEM TALK!? SAY HI FOR ME!!! FLOWERS ARE OUR BEST FRIENDS!!" – Papyrus, if the protagonist calls by the yellow flowers in the Garbage Dump.
 * 16) ↑ "i'll be 'frank' with you. as much as i like putting hot dogs on your head... thirty is just an excessive number. twenty-nine, now that's fine, but thirty... does it look like my arms can reach that high?" – Sans
 * 17) ↑ "so i keep 'em coming, and she keeps laughing. she's the best audience i've ever had. ... we kept telling each other jokes for hours. eventually, i had to leave. ... but she told me to come by again, and so i did. then i did again. and again. it's a thing now. telling bad jokes through the door. it rules." – Sans
 * 18) ↑ "haven't i done a great job protecting you? i mean, look at yourself. you haven't died a single time. hey, what's that look supposed to mean? am i wrong...?" – Sans
 * 19) ↑ "What's EXP? It's an acronym. It stands for 'execution points.' A way of quantifying the pain you have inflicted on others. When you kill someone, your EXP increases. When you have enough EXP, your LOVE increases. LOVE, too, is an acronym. It stands for 'Level of Violence.' A way of measuring someone's capacity to hurt. The more you kill, the easier it becomes to distance yourself. The more you distance yourself, the less you will hurt. The more easily you can bring yourself to hurt others." – Sans
 * 20) ↑ "You will be judged for every action. You will be judged for every EXP you earned." – Sans
 * 21) ↑ "your actions here... will determine the fate of the entire world. if you refuse to fight... asgore will take your soul and destroy humanity. but if you kill asgore and go home... monsters will remain trapped underground. what will you do?" – Sans
 * 22) ↑ "but you didn't get this far by giving up, did you? that's right. you have something called 'determination.' so as long as you hold on... so long as you do what's in your heart... i believe you can do the right thing." – Sans
 * 23) ↑ "so... i have a request for you. i kind of have a secret codeword that only i know. so if someone tells it to me... they'll have to be a time traveler. crazy, right?" – Sans
 * 24) ↑ "so, i guess you're qualified. here's the key to my room. it's time... you learned the truth." – Sans
 * 25) ↑ "truthfully, it doesn't really matter what you said. all that's important is that you were honest with yourself." – Sans
 * 26) ↑ "you act like you know what's gonna happen. like you've already experienced it all before. this is an odd thing to say, but... if you have some sort of special power... isn't it your responsibility to do the right thing?" – Sans
 * 27) ↑ Toriel:"Sans, did I tell you about the time Frisk flirted with me...? And then asked to call me 'mother?'" Sans:"oh boy." – Sans and Toriel in the epilogue.
 * 28) ↑ "well, i'll be straight-forward with you. my brother'd really like to see a human... so, y'know, it'd really help me out... if you kept pretending to be one." – Sans
 * 29) ↑ "hey, i really respect what you did back there." – Sans
 * 30) ↑ "A hooded figure watches the commotion from afar." – Flavor text from Shyren fight.
 * 31) ↑ "that expression that you're wearing... well, i won't grace it with a description." – Sans
 * 32) ↑ "sounds strange, but before all this i was secretly hoping we could be friends. i always thought the anomaly was doing this cause they were unhappy. and when they got what they wanted, they would stop all this. and maybe all they needed was... i dunno. some good food, some bad laughs, some nice friends." – Sans
 * 33) ↑ "A JEALOUS TROLL HAS BESIEGED MY ONLINE PERSONA, ALWAYS SENDING ME BAD PUNS IN A GOOFY FONT." – Papyrus
 * 34) ↑ "IT'S STRANGE. ASGORE, ALPHYS, METTATON, AND UNDYNE WENT AWAY. SANS SAYS THEY WENT ON VACATION. I HOPE THEY'RE HAVING FUN!!!" – Papyrus
 * 35) ↑ "welp. sorry, old lady. this is why i never make promises." – Sans
 * 36) ↑ "WAIT... THAT BAG OF DOG FOOD LOOKS FAMILIAR. I REMEMBER SEEING IT... IN SANS'S ROOM?" – Papyrus, on the bag of dog food in Alphys's lab.
 * 37) ↑ "hey. is your refrigerator running?" - Sans
 * 38) ↑ https://youtu.be/JHMdlpYYaOU
 * 39) ↑ "now my brother, papyrus..." - Sans
 * 40) ↑ "he's a human-hunting FANATIC." – Sans
 * 41) ↑ "papyrus would definitely use "aniki." i think. what's your take." – Toby Fox. September 10, 2015. Twitter