Keyes

Keith (キース Kīsu) is an Etherious of the Dark Guild Tartarus and a member of the Nine Demon Gates.

Appearance
Keith, as his alias "Black Priest" suggests, dresses in form-fitting robes with a high collar. The robe itself has a checkered pattern, and covers a collared shirt and tie that Keith wears beneath. Around his face and on his head, Keith wears an ornate head piece, revealing Tartarus' guild mark, covering his jaw and fanning out over his head almost like a crown.

Most notably though, Keith does not have a human face. Instead, his body seems to be that of a skeleton, with Keith possessing no nose, eyes or skin.

Personality
Keith is a very silent and mysterious demon, rarely saying a word, although he usually mutters. He has a calm and sadistic demeanor, even when he is about to face his enemies, as he eerily threatened Lucy, Wendy, Happy and Carla to hell before confronting them.

Keith also seems to acknowledge Silver and Gray's relationship, as he instantly recognized Gray when he encountered him.

Despite his seemingly calm personality, he has shown a more twisted side of his personality; Keith despises humans and treats them as tools for him to use for his Necromancy experiments. He sees feelings as humans' own weakness as he claims that feelings just gets in their way.

History
At one point in time, using his Curse, Keith resurrected hundreds of corpses, one of which included Silver Fullbuster, in an experiment to find out how much a corpse could behave like a living human.

Tartarus arc
Keith gathers with his fellow Nine Demon Gates members at the Tartarus headquarters. As they convene, the group are joined by Kyouka and Silver, both of whom were off on "special missions". Hearing that two of their other members, Jackal and Tempesta, are also out, the group move to put their plans against the Magic world into action.

After hearing about Jackal's successful mission involving the destruction of the entire Magic Council, Keith listens as some of the other Nine Demon Gates members argue over their lack of participation in the plan so far, though he chooses to remain out of the conversation, instead silently commenting about their dedication to Zeref. Later, in Tartarus headquarters, the Black Priest is among the several to sense Natsu Dragneel break into their base.

With the Fairy Tail Guild having landed on and entered their headquarters, Keith heads out to confront some of the guild members, soon finding Lucy, Wendy, Happy and Carla as they head out to deactivate Face. Approaching the Fairy Tail Mages, who stand scared at his skeleton-like appearance, Keith threatens the two women to hell, stating that they shall soon be corpses.

As he continues his advance, Keith is joined by Franmalth, who was hiding in the room as Lucy and Wendy investigated it. Before they can attack, Lucy summons both Taurus and Aries, and the two combine their abilities to form a cloud of wool, which temporarily blinds Keith and Franmalth, allowing Wendy and Lucy to fly from the room. However, Keith rapidly teleports from the control center, reappearing in front of the two once more. As he begins to cast a spell to take them out, he is struck from behind by Gray, though turns his body into a black mist to avoid receiving any physical damage. Reforming himself in front of Gray, Keith recognizes the Ice-Make Mage, and utters Silver's name. Confused, Gray casts an array of Ice-Make spells at Keith, though the Demon merely utilizes his mist body once more in order to avoid them, silently muttering that soon Face shall be activated as an annoyed Gray curses his abilities. Keith continues to battle Gray until Mard Geer activates a Curse that transforms the entire fortress; the Curse causing the enemy Fairy Tail Mage to sink into the ground and be trapped in the stone. Keith merely watches as the process is completed.

However, after Lucy manages to summon the Celestial Spirit King to her aid, the Alegria Curse is lifted from Cube, freeing the Fairy Tail members who were previously trapped. Coming to the aid of Torafusa when he is attacked by Gajeel, Keith attempts to strike the Iron Dragon Slayer from behind, though is stopped by Juvia, who swoops in to save her comrade. At the same time, both Silver and Gray join the fight, being followed soon after by Tempesta and Natsu. Facing off the Fairy Tail members, Keith prepares for a four-on-four battle.

Staring down his enemy, Keith watches as Silver and Tempesta spring into action, the former grabbing Gray and disappearing whilst the latter creates huge whirlwinds to blow their opponents about. As Gajeel and Torafusa later clash, Keith moves to intercept Natsu as the Dragon Slayer tries to help his friend, surprising him with his mist-like body and easily dodging Juvia's Water Slicer to attack her in return. As he regroups with his fellow Demons and watches Fairy Tail do the same, Keith silently mutters that nothing is over yet. Continuing his battle with the three Fairy Tail Mages, Keith shrugs off a punch from Natsu, his body yet again turning into a misty substance. When Natsu leaves him, Keith turns to attack Juvia once more with his khakkhara, striking her as she stands distracted. Hearing her mumble that she believes Gray is in danger, Keith comments that it will soon be the end of Gray's life, receiving a rage-filled glare from Juvia as he explains that Gray will lose himself in a calamity and follow the fate of his mentor, Ur. Glorifying Silver's Magic abilities, Keith aims an attack at Juvia as the Water Mage asks why a person with Demon slaying Magic would join a guild of Demons; Keith replies that it was all the whim of Mard Geer that Silver be accepted as a Demon Gate and strikes a distracted Juvia with yet another attack. In the midst of the battle, Keith lets Juvia know that Silver is, in fact, a corpse of Gray's father revived by the Demon.

Now rapidly assaulting Juvia, Keith states that they knew Silver was acting against them, but adds that they let him continue to act as his desire for revenge extended his life; calling him a fascinating puppet, Keith expresses his belief that humans are merely tools for his research. Making his body intangible, Keith removes himself from harm's way and tells Juvia that he will next use her corpse to kill all of her friends. Wrapping himself around her body, Keith tells her in response to her defiance to kill him, but mentions that if he does, Gray will once more be without a father; he then gleefully taunts Juvia whilst citing his belief that human emotions are foolish. With a final twist of his body, Keith absorbs Juvia but quickly realizes his folly, as her water body begins to struggle and move about inside him; Keith is then blown to pieces as Juvia forcefully exits his body, which in turn causes all affected by his Necromancer to cease functioning.

Curses and Abilities
Necromancer (死人使い, ネクロマンサー, Nekuromansā): Using this Curse, Keith has necromantic capacities, which allows him to revive and control a deceased person, as seen when he used Crawford Seam to remotely activate Face. Keith is able to reanimate hundreds of corpses at a time, which allowed him determine how much a corpse could behave like its former self. However, corpses revived under Keith's control may only exist for a limited time unless they possess a driving force, as Silver's desire for revenge against Demons allowed him to stay reanimated much longer than other corpses. Furthermore, if Keith is defeated, corpses under his control would cease functioning.

Magical Barrier Particles: Keith's body is made up of thick black particles, allowing him to move similar to a mist and cause both Magic deficiency and illness, as seen after Juvia forcibly exited his body. Keith does so in order to avoid physical and magical attacks. The said ability allows Keith to deform and reform his body seemingly at will, though he has also been seen utilizing the ability almost unconsciously, being able to dodge a sneak attack by Gray with no effort at all by morphing his body as soon as the Ice-Make Mage made contact with it. Offensively, Keith can manipulate the poisonous anti-Magic particles in various ways such as spiraling currents, a wave, or an explosion, to attack opponents.

Equipment
Khakkhara: Keith carries around a Khakkhara, which he uses to attack opponents, able to injure even Juvia's water body, as well as manipulate the Magical Barrier Particles that compose his body to be sent at the target.

Quotes

 * (To Lucy Heartfilia and Wendy Marvell) "You Maiden Faries who have fallen into Hades shall become corpses and drift away in purgatory."
 * (To Juvia Lockser about Gray Fullbuster) "I can see it... The power of that calamity once again bringing forth that despair... And so in the end, the young boy will choose the same fate as his master."
 * (To Juvia Lockser) "This is my story. A story in which I try to create more perfect dead bodies."
 * (To Juvia Lockser) "Such is Human foolishness. Such is the nature of Humans. Emotions are but impediments of reason. Unsightly bundles of ego."

Battles & Events

 * Gray Fullbuster vs. Keith