Sans is a skeleton, just like his Undertale Counterpart. His clothes are very similar to that of his counterpart. He wears a black winter hoodie that has white fur, which is usually rough in appearance. Underneath, he wears a dark gray shirt with a red bio-hazard symbol on it. He also wears black running shorts with white stripes on them. He wears red and white sneakers as well. Unlike his Undertale counterpart, he uses weapons. Although he still has psychokinesis, teleportation, he mainly uses his twin submachine guns and his katana in combat. He can also summon Gaster Blasters. However, these are dark gray in color, and they bear four red eyes each. They are also much larger than those of the original Sans. He is also much taller than Classic!Sans, at 5'7, mainly due to his legs being much longer than Classic Sans'. He also wears a red bandana over his mouth.
Sans is much more energetic and responsible than the Original Sans, but he also enjoys taking naps. He likes to drink maple syrup instead of ketchup, and still loves to tell puns, despite usually being serious. He also is more caring for his brother Papyrus, as he greatly fears losing him to Asgore. Sans also loves fighting, and frequently practices fighting with Papyrus. A weird thing he does is hide in refrigerators. Though it may seem bizzare, it's only because he's so used to the cold in Snowdin, and doesn't adapt well in warmer temperatures.
Sans and Papyrus were the two children of Arial and W. D. Gaster. Long ago, Arial was deployed into battle to fight in the Human-Monster war. However, she did not survive. To prevent further harm to be dealt upon the already damaged kingdom and to convince them to harvest human souls to break the barrier, Asgore told Sans and Papyrus that a human had killed their mother. They believed him until they later found out that another monster had killed her. They learned she gave sympathy to an injured human and helped him to safety, but she was seen by another monster, who saw her selfless act as betrayal, and killed her on the spot. Bitter and angry at Asgore's lie, the skeleton brothers left Asgore's Leadership. They were later found by Alphys, Toriel, and Grillby, who joined them in their rebellion to overthrow Asgore. They also agreed to protect any human who fell down from Mt. Ebott.
("Spoilers" ahead (but nothing for Roguetale has been released))
In Roguetale, when Frisk falls from Mt. Ebott, his first instinct is to run up to her and come to her aid. He asks her if she is alright, and then proceeds to either help her up or carry her to the exit of the Ruins. At the end of the Ruins, Toriel, Mettaton, Alphys, and Grillby are waiting there. They turn to Frisk and greet her. Toriel tells her that they mean no harm, and she warns her about Asgore. Frisk joins Sans, Papyrus, and Mettaton in an attack on Asgore's castle, but the plan fails. They are driven back to the Ruins where they form a new plan.
Sans' powers are very similar to those of his Undertale Counterpart. He can summon and manipulate bones (usually femurs), and he can also summon and manipulate Gaster Blasters. His blasters are dark gray in hue and each have four eyes with red pupils. They are also larger than Sans himself, thus being much stronger than those of the Original Sans. The blasters are called "Gatling Blasters" due to a gatling cannon in their mouths that spins and fires a large barrage of energy blasts. Sans can also take control of one's soul and move them around using psychokinesis, but this ability is useless against soulless beings, such as Terracus. (Although it will work on Spectron, as he still has a soul.) He can also teleport at will. Despite having all of these abilities, he mainly relies on weapons, such as his katana and submachine gun.
- He is usually overconfident and thinks he can take on anyone on his own. Most of the time, he ends up wrong.
- He is terrified of Error!Sans.
- He has A.D.D, and will sometimes zone out in the middle of battle, leaving him wide open to attack.
- When he gains a certain level or anger, his attacks will become based on impulse, not thought. However, his attacks also become more powerful if he's angry.
- He doesn't know when he should stop talking or to not talk at all. For example, he will sometimes annoy Error, but when he does, he is never thinking.
- He's more of a pack fighter, and does not fight as well alone.
- He mainly relies on his weapons for attack, and only uses his true powers if absolutely necessary.
Papyrus is Sans' younger brother. They constantly look out for each other, and deeply care for each other.
Sans deeply cares about Frisk, and acts as her guardian. He also secretly has a crush on her.
Sans shares a hatred with Papyrus for Asgore. This is because of their mother's death by the hands of a fellow monster soldier.
Grillby is one of Sans' only monster friends. They were best friends even before Sans and Papyrus left Asgore's leadership.
Ink visited Sans in his AU Roguetale and befriended him. Although sworn allies, Ink refuses to kill Asgore, despite Sans' requests.
Rogue!Sans is terrified of Error, being scared he will destroy his universe, but he will taunt him if Vincent becomes involved, as he guards Roguetale, and is more than capable of taking Error out.
Sans hates Spectron, and vowed to slay him once and for all, despite it being a nigh-impossible task due to Spectron's immortality.