Zoldeo is a member of Grimoire Heart and one of the Seven Kin of Purgatory—a distinction he earned through an unconventional and forbidden method: possessing Capricorn's body.
He came into possession of Capricorn's key after Layla Heartfilia stepped back from active Spirit summoning. The original plan was simple enough—he'd keep it safe until Lucy was old enough to take over. But something went wrong. Zoldeo became corrupted, consumed by darkness, and made a choice that crossed a serious line. He used Human Subordination Magic on a Celestial Spirit, breaking one of their most important taboos, and managed to possess Capricorn's body in the process. This possession is actually the only reason Capricorn was able to remain in the human world for seventeen years; without Zoldeo inhabiting him, it wouldn't have been possible.
Eventually Hades found him and brought him into the fold. Zoldeo became one of Grimoire Heart's most powerful members, standing among the Seven Kin of Purgatory.
Content compiled by AnimeList.moe from publicly available sources.
