The resident playboy of Fairy Tail who is revealed to be Leo, one of the Celestial Spirits banned from the Spirit World.
Loke is a stellar spirit whose spirit name is Leo, one of the 12 Zodiacs. He blames himself for the death of his former abusive master Karen. When he was summoned, he went on strike, never returning to the spirit world until she released him and her other spirit, Aries, from their contract. Because Loke wouldn't return to the spirit world, Karen was unable to summon her other spirits and could no longer take missions. But after learning that she could summon more than one spirit by using a large amount of magic, she tried going on a mission without permission from her master, Bob, and was killed from her inability to handle the magic it took to summon two spirits at once.
When Lucy first joined the guild, he was scared of her for being a Celestial Spirit mage. Since Loke had been banished from the spirit world for indirectly killing Karen, he disguised himself as a human, to mask his real identity, and joined Fairy Tail as a mage. But he was slowly dying because spirits could not survive in the human world. Lucy eventually learns of his past and sympathizes with him. She summons all her spirits and convinces the Celestial Spirit King to let Loke return. When he returns, his golden key is given to Lucy.
Loke, who is created by Hiro Mashima, has no information on what inspires the author to create him. Even without the direct notes from Mashima, it is assumed that Loke's personality is similar to his previous characters, Hamrio Musica, from Rave Master. They both have a flirtatious personality.
Due to Lucy Heartphilia's refusal to let Loke die, her act of kindness has made the King of Celestial Spirits grant amnesty to Loke on one condition: Loke must protect Lucy with his life.