Progenitor

A Progenitor is basically what happens when a Keyblade Wielder has the negativity extracted from their heart through some means, normally by an evil wielder. But those who fail in proving themselves worthy of wielding the Keyblade, or succeed in doing so only to be defeated in a gruesome manner after claiming it can become a Progenitor. When a Keyblade Wielder has their heart damaged and the negativity extracted is from them, they become an utterly different person. One made up of darkness, with a damaged heart only capable of feeling pain that feeds off the negativity of itself and others. Despite being inherently dark entities, a Keyblade follows the heart of it's wielder. Even if it is damaged beyond repair..