Sans

Sans is a skeleton that with his brother Papyrus, showed up in the town of Snowdin out of nowhere. Sans is laid-back and lazy. A human child named Frisk showed up in the Underground. When they entered Snowdin for the first time, Sans was there to meet them. Sans told them about Papyrus, who hoped to capture a human to become a member of the Underground's Royal Guard and asked if Frisk would show themself to Papyrus just to make him happy to see a human. Frisk agreed, and while Papyrus didn't capture them, Frisk befriended the skeleton brothers. However, Sans still hides several secrets and a large amount of power and skill underneath his laziness, being the one who killed Flowey more times than any monster.

the only way to fight Sans is in the genocide route where Sans is the only one left before they reach King Asgore, break the barrier, and escape to cause havoc on the surface. Sans states that he knows about the player's ability to save and load the game, effectively letting them reset the timeline, and hopes that, even though he can't kill them since they'll just come back, he can still be such a difficult and unfair opponent to beat, that the player just quits the game. It is here that the reason for Sans' laziness is revealed. Because of his knowledge of the save ability, Sans has adopted an extremely nihilistic worldview. He believes that, because time can be reset just by the will of one person, nothing he does matters, since it could be undone in an instant.

Appearance Sans appears to be a small and thick-boned skeleton, slightly taller than Frisk. Sans is always seen wearing a light-blue parka with a grey hood with black short pants with white lines on them, a white tank-top and salmon moccasins.

He has a large, rounded skull shaped similarly to a slice of bread and has large bags under his eye sockets, which have white glowing pupils floating in them. His face is constantly in a smile. His mood is shown through his eyes instead of any facial gestures due to his mouth being apparently locked in a smile, though most head canons will show him frowning occasionally.

Powers & Abilities Bones: One of Sans' most common attack is to summon bones to attack his opponent. Sans can summon large groups of them easily in complex patterns with great speed, making these attacks some of the hardest to dodge in the entire game. Sans can also summon blue bones that only deal damage when moving, harmlessly passing through if you're still. Sans' bones can be used as projectiles and platforms, the bones don't do much damage, only 1 damage point per hit, but his karmic retribution (see ability 3) and the number of the makes the fight hard, nonetheless. Gaster Blasters: Portable laser cannons shaped like dragon skulls that Sans can summon at will. They levitate off the ground and fire at Sans' will, and Sans can summon as many as he wants. He can send out multiple at a time and surround his foe in a circle, for multiple blaster shots. Soul Manipulation: Blue Mode: the second most common attack for sans, Blue Mode grants Sans the ability to make enemy souls affected by gravity. While affected by Blue Mode, enemies have their movement heavily restricted and are only able to jump to move. Sans can also use this to lift and move his opponent's soul, letting him slam them around with relatively small physical movements compared to what he's doing. Karmic Retribution [KR]: Sans' bones and Gaster Blaster attacks inflict the Karmic Retribution effect [KR]. KR acts like poison, marking a portion of your health bar pink, which will slowly disappear, giving you a chance to heal before you die if your entire bar turns pink. KR is what makes the Sans fight commonly known as the hardest in the game. Canon information about it is pretty vague. We can infer that KR stand for Karmic Retribution or similar, and it likely only affects people who have done evil. The more evil, the more retribution. Though, this is all speculation, and there is no canon explanation. Larger Than Average Stomach: Sans can consume more hot dogs than any other monster within the Underground. As a skeleton, it's unknown where the hot dogs go, as Sans lacks a digestive tract. Teleportation: Sans can teleport himself, his opponents and his attacks at will. He normally calls this a "Shortcut". He uses this ability in battle to dodge attacks and to make it harder to dodge his attacks. Intelligence: Sans is one of the smartest characters in the game, there are hints that he's a scientist in the secret room behind his house. There's a Quantum Physics book found in his house, and he's friends with the royal scientist Alphys. Fourth Wall Awareness: Sans is fully aware of the fourth wall and that he is in a video game, he abuses the RPG (Role-Playing Game) turn system at the end of the battle by dragging out his own turn "forever" so you can't take yours. He is fully aware of timeline resets as well, taunting the player by counting how many times they have died. Manipulation: Sans is clever and manipulative when he needs to be, even talking down his brother from capturing you and bringing you to Undyne. Scientific Knowledge: Sans also seems to have a scientific mind, given the Quantum Physics book in his house, commonly theorized to be him trying to escape the resets. His friendship with the royal scientist, Alphys also reinforces this idea.