Sans is the brother of Papyrus, and a major character in a fan-made Undertale AU, Underswap. It is unknown if he is older, younger, or the same age as Papyrus. His motivations are to capture a human so that he can become an official member of the Royal Guard; a very prestigious job.

He has a dream of seeing a human. A couple of his disadvantages are that he is almost as weak as Canon Sans, leading to the guard denying him a position in the Royal Guard. However, he is very cheerful and much more energetic than Undertale Sans. He is also very positive and enjoys making tacos for his friends.

His stats are alike to Canon Sans', being 1 HP, 1 ATK, and 1 DEF. He also retains Canon Sans' Karmic Retribution.[1]

Underswap Sans is similar to Canon Papyrus in a lot of ways, but there are also some differences! For example, instead of "NYEH HEH HEH!" or "WOWIE!", Underswap Sans will say "MWEH HEH HEH!" or "WOWZERS!" Also Underswap Sans has a liking for riddles instead of puzzles. He also collects Sci-Fi figures instead of action figures. [2]

He is often referred to as "Blueberry" by fans because most of them find him cute, along with the fact that most of his clothing is blue. However, Blueberry is a fanon rendition of Underswap Sans. He appears to be more cute, innocent, and sometimes more baby-like, unlike the original Underswap Sans. Blueberry is not canon to Underswap and is not the correct portrayal of Underswap Sans. 

Overworld AppearanceEdit

His arms are by his sides, and he appears standing up straight and still, facing the player like Undertale Sans. He is smiling, but his dimples are missing. (Though the edges of his mouth are tilted up to suggest something like dimples). He wears a blue bandana that appears to have a small hole close to the center. Whether this is an accident or not is up for debate. He also wears gloves like Undertale Papyrus in his battle scene, but they seem to be missing in his overworld figure. He wears a gray sleeveless shirt with a white t-shirt underneath, along with gray shoulder pads with baby blue outlining. He wears pants with a slightly faded blue look to them, and he wears blue shoes that match the color of his bandana.

In Battle AppearanceEdit

He stands in the same position as Undertale Papyrus but is much shorter. Aside from his dimpled smile, (which is similar to, or if not exactly like Undertale Sans'), his facial expression is mostly like Undertale Papyrus'. His battle sprite reveals that the bandana he is wearing ties up behind his left shoulder, which is something that is not seen on his overworld figure.

Relationships Edit


When Sans first met Chara, he immediately wanted to be friends with them. He is very happy to have Chara as a friend, but disappointed because he cannot join the Royal Guard for befriending Chara; a human.


Sans is the brother of Papyrus. They are very close even though Papyrus likes to joke around which oftentimes annoys Sans a lot. However, to Papyrus, Sans is the most important thing in the world. Papyrus is generally seen as Sans' protector, but heavily affected by his knowledge of the timelines, expecting to see Sans again even if they were to both die.


Sans and Alphys are best friends. Sans wants to join the Royal Guard, but Alphys secretly will not let him since she cares about Sans and refuses to see him get hurt because his stats are too weak in battle. They hang out all the time. Alphys is also the one who is training him.[3]


Sans starts a Temmie fan club, as told by Temmie themselves in the Neutral Route. It is known that Temmie does not like Sans, but it is unknown what Sans thinks of Temmie.

Toriel Edit

Sans and Queen Toriel are told to also be best friend just like the Canon Sans.

Theme Songs Edit

The intended theme for Underswap Sans would be one with a "Song That Might Play When You Fight Sans" leitmotif, therefore, making Passive Megalovania non-canon to Underswap.[4]

For Mweh Heh Heh! and Bonequarrel, click on this link:

For Passive Megalovania, click on this link:

References Edit