"you've met with a terrible fate, kiddo. "
Sans The Happy Mask SalesSkeleton is a recurring character in Majoratale. He travels through different lands searching and collecting a wide variety of masks. He is most known for his erratic, sudden mood swings and is considered to be one of the more unnerving characters in the series, mostly because of his many mysterious and abnormal behaviors.
Prior to the events of Majoratale, he was continuing his search of masks as he traveled through the woods. However, he was suddenly ambushed by the Human. While he was unconscious, the imp went through the many masks that the salesman possessed, and eventually took a cursed mask known as Chara's Mask.
Viz Media Edition
This information is based on alternate scenes or materials, and is not considered canon within the overall plot of the AU.
"ho ho... they're off to confront that little demon. now for the real show. if I can only get that mask back, i'll no longer have a need for this world. i just move on. ho... ho ho ho... "
– Sans (Viz Media Version)
In the Majoratale manga, Sans is quite different. Though his role appears exactly the same as in the original AU at first, towards the final battle with Chara's Mask, he is shown far more sinister than previously. After the battle, the Happy Mask Sans appears before Asriel (still wearing the Hyperdeath's Mask) to take his mask. Asriel strikes out at him with his Sword and tells him to leave, slicing various masks in half, possibly in an attempt to strike Chara's Mask. He misses, however, and the mysterious skeleton picks up the mask and fades away laughing.