Batsy

An interpretation of WD Gaster from Undertale. His original form is that of a bat-pangolin(-puma) Boss Monster. Because of this, he is not related to Sans or Papyrus but he did adopt them when they were very young. In Basty's timeline Papyrus is the older brother.

Batsy fought in the human-monster war, as a healer. Though, as he is a Boss Monster he was also used as a heavy hitter in the front lines, with his unique poison ability.

Name: Bastien Gaster
Fragment Designation: Batsy
Age: Old. He doesn’t keep track anymore. (Old enough to have been in the Monster-Human War)
Species: Pangolin-Bat-Puma Monster (+some skeleton)
SOUL Type: Boss Monster; VOID Detizen
Height: 6’3 regularly; fluctuating 6’ in VOID form
Abilities: Inherent Magic - Healing, Acid, Gravity Manipulation, and Contruts; VOID Magic - Timeline/Universe Hopping & Teleportation via shadows, Personal Void “Inventory” hammerspace.
Personality: Warm, caring, and open. He’s level-headed and easy-going, though can be very protective over people he cares for. He can be goofy and likes to crack jokes. Hard to get truly angry, he prefers to be the peace-keeper and supportive party. He can sometimes get distant and stand-off-ish but this is usually short-lived.

Background:
In a now destroyed timeline, there was a Snowdin school teacher named Bastien Gaster, and a royal scientist named Wingdings Serif. When certain events came to pass and the Story was set in motion, the Game dictated the role of “WD Gaster” to be filled. With two viable candidates, the Game simply merged the two into a single entity. Being a Boss, Bastien’s SOUL took unintentional dominance over the fusion and Wingdings ceased to be, but not without leaving permanent alterations to Bastien’s physical form and memories. There are still traces of Wingdings within the new entity’s personality, though this tends to be more evident when in his VOID form.

Batsy’s memories of how he came to be in the VOID are fuzzy at best, and his recollections of his past are hazy. There’s some part of him who feels like something is wrong. But, as of now, he is simply making the best of his current existence.