Intermediate

An Intermediate is a powerful being, and is also the name of any person or creature who possess an Intermediate SOUL.

Origins
The first-ever known Intermediate SOUL possessor was and who it’s first user was within the Undertale universes was a confusing argument. At first, it was claimed by the then-Royal Scientist of the Kingdom of Monsters’, Dr. W.D Gaster, that the first possessor of an Intermediate SOUL was, for a short while, the Kingdom of Monsters’ Prince, Asriel Dreemurr. This claim was further backed by an “unusually high amount of energy” which was “radiating” from the SOUL, traced by Gaster’s two pupils, as Asriel and the First Human, another well-known individual within the kingdom, combined their SOULS in attempt to cross the Barrier.

Another claim was that Sans, a skeleton serving as one of Gaster’s closest pupils, was the first possessor of an Intermediate SOUL. The same evidence made in Asriel’s case was applied onto Sans, although Gaster personally jested that Sans “was too lazy to even prove such a quandary.”

The final claim was made with Flowey (Aster Abbot), another notable individual within the Underground, who was previously said to “not exist before.” Unlike the evidence from the first two disputed owners, Flowey’s Intermediate SOUL was tested with the Barrier, which does not usually allow a normal human or monster’s SOUL to leave.

It was eventually concluded that Asriel was the first possessor of an Intermediate SOUL, and that Flowey and Sans were the second and third respectively to obtain Intermediate SOULs.

Subsequently, during the multi-national effort of Project ASRIEL, three other human Intermediates, and one other creature, also an Intermediate, were introduced, and were added to the growing list of Intermediates within the Undertale universes. As of now, they are unknown, but rumor has it that one “ripped off Sans’ sprite and made it human-like”, the other was a mother figure, another was a truffle-baking kind girl, and that the other creature was a bipedal, large, penguin-like-ish baby Harp seal.

These Intermediates would eventually gather to form The Intermediate Council in 2015.