Kobalt Gavronskii, or Marshmallow, was a purportedly deleted character from the series Pineapple Soda. Originally, he was created with the intention of being added to the main trio alongside Pumpkin and Lime. His character art where he was featured alongside the two of them was suddenly deleted and all mentions of his character removed from official sources shortly after his release. This sparked controversy among fans and his character's deletion remains a subject of debate and common inquiry from fans both online and in convention panels today. Marshmallow's gap in the trio of trios wasn't filled until nearly four years later when PB became his official replacement. This was despite PB having only played a minor supporting role until that point in the series. Fandom outcry urging the return of Marshmallow spurred a response from Erin Foraker, one of the head writers of the series and the creator of the character Marshmallow:
". . . Marshmallow DOES get a couple big roles in some of the larger and more outlandish Sagas. He even becomes the main villain once! Never fear. He will get his spot in the limelight - I’ve made sure of it." 
Marshmallow was a very short, somewhat androgynous character with jovial features. He was illustrated as having almost albino-like combination of pink eyes and gray hair resembling a powdered wig. His hairstyle having taken apparent inspiration from the kemonomimi-style* ears of Eastern folklore, or perhaps from the feather stylings on the crown of a great horned owl. Marshmallow had exceptionally long and light coloured eyelashes and was drawn in an exaggerated cartoon style not found elsewhere in the overarching series.
This character's personality is not well known due to his general absence from the series. In concept, he was often drawn attributed to the cute kawaii-esque mannerisms of the Moe* anime movement, but sometimes depicted as sinister or tyrannical. It's possible he was intended to play the character archetype of yandere* in Japanese anime and was then scrapped as the series began to become more notably comic book styled and Western.
PB's global character number is the same as the official listing number for Marshmallow; both appear as character #008 at different points in development.
Despite not technically being a character, Marshmallow can be reached through the official discord by typing @ + his character icon or by mentioning his name in the ask-the-characters channel.
This is something that cannot be done with many extant or confirmed characters, such as Sugar as of this current date.