Mard Geer Tartaros

Appearance
Mard Geer is tall, lean and has the appearance of a young man. Often seen wearing a smirk, Mard's black hair is long and wavy, reaching his shoulders even whilst the majority is tied up in a very large ponytail. Additionally, his messy bangs all but obscure his dark, slanted eyes.

For clothing, Mard's dons a long, black jacket trimmed with a light-colored flame pattern; the lapels are a matching lighter color as well. The cuffs of his jacket are rolled up, revealing a light-colored inside, which contrasts the black outside of his jacket, and have a black line cutting through the edge of the fabric. The jacket itself is tattered and splits into four torn fabric segments at the tail. Beneath the jacket, Mard wears a frilly black v-necked shirt, lined in a lighter color, that closes down the middle and is adorned with a buckle just below his clavicle; just below this is a piece of fabric that Mard keeps over this shirt but under his jacket, that circles the majority of the lower half of his torso. The rest of his attire is simple, consisting of light-colored pants that lay lazily over the top of rather plain black boots and have, on each leg, a seam running down the middle, as well as two pairs of buckles that form an X on the thigh and lower calf. However, the buckles on each thigh later disappear, leaving only the ones on each calf.

Like other Etherious, Mard is able to transform into his true, more powerful form. His body becomes more muscular, and his skin darkens and gains the ragged pattern of his cloak. He gains long, dark horns on his forehead, jagged teeth, and retains his ponytail. Mard's fingers are replaced with claws and his ears become elongated and elf-like. He gains large, bat-like wings that are both light and dark in color. Feathers also sprout from his wrists and collar.

Personality
Often seen smirking, Mard is a cool, collected, yet arrogant man who plays himself off as being extremely intelligent; he quite regularly refers to himself in the third person. Also, much like the rest of his kind, Mard belittles humans, and thinks of them as nothing more than insects. Indeed, he finds the mere thought of letting a human live when given the chance to kill them a tragedy, and is not above torturing his subordinates when they cause him any sort of inconvenience (ironically, not much later, he begins to understand, after fighting Sting and Rogue, that toying with humans can be quite enjoyable, as he ultimately finds their ignorance and belief in things such as hope incredibly amusing). Additionally, Mard takes great pride in being one of Zeref's Etherious; he also has a habit of referring to Cube as his "garden", and appears to love it enough to make Fairy Tail pay for bringing harm to it, even though he noted that ultimately, it didn't matter in the slightest. However, after many outsiders intruded and Cube was destroyed, Mard began to feel, for the first time in years, anger, an emotion he expressed himself to have forgotten long ago.

Mard is also rather intolerant of human emotions, having decided to kill his for the sake of putting his intellectual side first. He also cares a great deal for E N D's safety whilst in book form, setting his tome down before proceeding to unleash his fury against Natsu and the Twin Dragons, as he was unsure of what his rage would do to the book. When throwing away his calm nature, Mard's arrogance grows in leaps and bounds, as after he emerged unscathed from a full-scale assault from his Dragon Slayer opponents, he merely sat upon his throne and goaded them by saying that he has yet to use his Etherious Form, as well as that they should give up. Though when variables that he did not predict come into his equation, such as Gray receiving Silver's Ice Devil Slayer powers, even he can lose his composure and exhibit shock and awe.

History
Like the other Etherious, Mard Geer was created by Zeref as a way for the man to die and had upon his genes inscribed an inherent desire to "return to Zeref" and fulfill the man's wish. To accomplish the means to this end, Mard created the Curse Memento Mori to destroy the barriers between life and death, as Zeref is immortal and cannot die by conventional means, and simply erase his existence from this world.

At some point following his creation, Mard Geer came into contact with the Celestial Spirit King, sparking a rivalry of sorts between the two. Additionally, he came to know of Scavenger and Igneel.

Sometime following E N D's departure for the future, Mard Geer, unaware of what happened to E N D and not knowing what he looked like, stumbled across his sealed tome and used it to rally and unify the other Etherious together under "E N D's will", and thus formed Tartaros (which he apparently named after himself), resolving to act as its leader until they "revived" E N D, proclaiming the Etherious to be their Guild Master. At some point after this, the Demons of Tartaros made contracts with the Underworld King, enabling them to be reborn upon death at Hell's Core.

According to Keyes, Mard Geer acknowledged Silver Fullbuster's power (sometime after his "revival") as a Devil Slayer and granted him the title as one of the Nine Demon Gates either by his whim or that the Exorcist Mage act as a deterrent for the Demons of Tartaros.

Tartaros arc
Mard Geer appears for the first time inside of Tartaros' HQ. Sitting on a throne in his room and holding a book with the letters "E N D" written on the cover, Mard Geer talks about Zeref's Demons, the Etherious: beings superior to humans. Seemingly reassuring the Master, Mard Geer states that the darkness of Hell's gate will soon appear and eat up the world's light.

Shortly after, Mard Geer is approached by Kyôka, who informs him that the plan to activate Face failed, and that the resurrection of Franmalth and Ezel was halted by members of Fairy Tail. Seemingly bemused, Mard Geer tells Kyôka that Seilah too was only just defeated, causing the Demon woman to ask for E N D to be summoned to assist them; however, Mard Geer informs her that there is too much Magic Power present in the world for E N D to properly resuscitate, and, though Kyôka reminds him that that was the entire point of using Face, he states that their plans will still come to fruition. Asking Kyôka about their goals as a guild, Mard Geer proceeds to attack the woman when he finds out that she was "playing with humans", a punishment he states she deserves for daring to interact with them too much. As Kyôka tries to thank him for righting her wrong ways, Mard Geer decides that he may have to use Alegria given the current situation. Making his move, Mard Geer hijacks Warren Rocko's Telepathy, and uses it to introduce himself to the Fairy Tail Guild. Bidding them farewell, the man makes use of Alegria, which proceeds to warp and deform Cube, swallowing everything and everyone present inside. Kyôka warns the Demon that he is sacrificing their own troops, though Mard Geer seems not to care, berating the human race as he waits for his command to finish. However, as the morphing of Cube comes to an end, Mard Geer senses that one of the Fairy Tail Mages managed to avoid being captured, laughing as he debates whether or not Lucy Heartfilia has good or bad luck for being able to slip free from Alegria's grasp.

Mard Geer then uses Telepathy one more time, informing the members of Tartaros that Alegria has gotten rid of the intruders so the Face project can continue. However, he also reveals that Lucy has escaped the effects of Alegria and promises that if any of the soldiers kills her, they will receive the title of Nine Demon Gates, or in the case of the current Nine Demon Gates, a prize; this prompts the entirety of Tartaros to chase after the Mage. Mard Geer later stands before the Celestial Spirit King, after the latter appears thanks to Lucy's sacrifice and destroys the transformed Cube.

He expresses his surprise that someone was able to summon the Celestial Spirit King and then explains to him that the book he's carrying is the soul of E N D. The Celestial Spirit King then asks about their motive and Mard Geer reveals to him that they are trying to revive their Master and reunite with Zeref. The Celestial Spirit King then questions if this is the reason for Lucy's wounds and sorrow, and when Mard Geer confirms it, he is attacked by the spirit's sword. Mard Geer envelops himself in a sphere of Curse Power and strikes the Celestial Spirit King, however, the latter counters it with ease. Wasting no time, Mard Geer summons thorns to pierce through the spirit's body, claiming this to be the end, but the Celestial Spirit King cuts through them and replies with an attack of his own: Meteor Blade. The technique causes great destruction, although it misses its target, Mard Geer, who commends the king for his efforts. Mard Geer and the Celestial Spirit King continue clashing as the latter lends Aquarius' power to Lucy Heartfilia.

Mard Geer and the Celestial Spirit King continue the battle, with the former noting that the latter is becoming slower. Mard Geer attacks with his Curse one more time, claiming that this is the end, however, the Celestial Spirit King defends himself and proceeds casting Galaxia Blade. While shielding himself, Mard Geer smirks, asking whether the Celestial Spirit King is willing to sacrifice Lucy, however, it soon turns out that this spell instead cancelled Alegria. As the Celestial Spirit King begins vanishing, Mard Geer starts turning into stone. As he gives a warning that the malice for humankind won't be forgotten, Mard Geer ends up being fully petrified. After it is revealed that there are several more Face devices, Mard Geer, albeit still petrified, smirks that this is the true appearance of the continent's Magic Pulse Weapon.

Having been completely freed from his petrification, Mard Geer walks back into the ruined Cube, stumbling across Erza and Minerva just as the former has seemingly ruined the latter's resolve to fight. Hearing them speak about life and death, Mard Geer interrupts, calling the two women garbage and vowing to clean them out. He blasts Erza away seconds later, and, after flinging Minerva into the air with his Curse, moves to blow her up as well; however, the woman is saved from his attack by Sting and Rogue, who arrive just in time to protect her.

With Mard Geer watching on, Sting and Rogue vow to return Minerva to their guild and ask Erza to take her, Lector and Frosch to safety, preparing to stay and fight on their own. Seemingly letting them do as they please, Mard Geer calmly states that their actions mean nothing, as the Magic world will be destroyed in under an hour when the 3,000 continent-wide Face devices are fired. Minerva tries to calm the group by reminding them that Face weapons need to be activated manually and that such a feat can't be achieved, though Mard Geer interrupts and explains that through Keyes' necromancy and Crawford Seam, Tartaros have the capacity to remotely set all of the weapons off at the same time. Believing him, Sting and Rogue tell Erza to go and stop the plan, and together they rush Mard Geer and engage him in battle. Whipping around the Tartaros Demon, the Dragon Slayers try to attack from both sides, though Mard Geer continuously evades their assaults with carefully timed maneuvers and parries. Flinging Rogue backwards into Sting, Mard Geer powers up an explosive spell and attempts to blow the duo away, commenting that he hates that Dragon Slayer Magic is used by such petty humans. Sting and Rogue—albeit taking the blow—both continue to stand, angry in return that Mard Geer hurt their friends.

Mard Geer is then quickly subjected to more attacks from the Dragon Slayer duo that, like before, leave him less than phased. As he takes the hits, Mard Geer states that he understands why Kyôka enjoyed playing with humans so much: it is because they do not see their demises, they act out of emotion, and are oblivious to how frail and weak they truly are; all things Mard Geer finds blissfully ignorant. As the fight continues, Mard Geer does eventually give Sting and Rogue credit for being at least competent in their Dragon Slayer Magic, as few match him in battle. However, he follows this up by gloatingly remarking that he can see why the two would be so wrongly full of themselves and confident.

Some time later, Mard Geer temporarily interrupts the battle to comment on Scavenger's sudden arrival. Noting that it exceeds his wildest imagination, Mard Geer wonders what exactly lured the Dragon King, Demons or even Zeref himself. Mard Geer notes that even he can't tell what will happen now that Acnologia has appeared. He then realizes that he wishes to destroy E N D before its resurrection and ponders whether it is because it fears E N D.

Shortly after, Igneel emerges from Natsu's body and engages the black Dragon over the Tartaros ruins. Watching the two fight, Mard Geer vows to let neither get in the way of his plans, and remarks that he has made slight alterations so that both Dragons will be erased from history. However, as he watches the spectacle above, Igneel too notices him in return, and asks Natsu to retrieve the book of E N D from Mard Geer's possession. With a smile on his face, Mard Geer then watches as Natsu launches himself towards him, ready to fight.

Mard Geer is swiftly attacked by Dragon Slayer, and is shocked to hear that Igneel is Natsu's father. Pushed back, the Demon King retaliates with his thorns, but these are evaded by Natsu, who proceeds to punch him in the face as he demands the Book of E N D be handed over. Grounded, Mard Geer telepathically contacts Kyôka and tells her to form an Organic Link with the Face controls in order to speed up the firing of Face with her body; this will wipe the abilities of both the Dragons and Mages faster, and give them the edge in their fight. Kyôka questions the plan, as to fuse with Face will forfeit her life, though Mard Geer disregards this, smiling as Kyôka complies with his demands.

With Face seemingly sorted, Mard Geer continues his fight against Natsu, and, calling the Dragon Slayer a false Dragon, pushes the Fairy Tail Mage down into the ruins of Cube. Leaping after him, Mard Geer tries to finish the falling Dragon Slayer off, though is stopped by Sting and Rogue, who rush in to protect Natsu. Waiting as the three converse, Mard Geer is then attacked simultaneously by the three men, who decide to take him on together. To begin with, the Underworld King manages to hold them back, but, after some skilled teamwork between the three, is eventually beaten back. Pulling himself from the ruins, Mard Geer smiles sadistically at the trio as he declares that he is finally mad.

Mard Geer nearly loses control of himself, but sits on his throne to calm himself down while apologizing to Master E N D as he puts down the book he has been carrying all this time, citing that he doesn't like to let his emotions run wild. He then attacks from his chair with a surprising increase of power. Natsu manages to get close a few times but none of his attacks even phase Mard Geer. Even after being launched from his throne by Natsu to give Sting and Rogue an opening for a combined attack, Mard Geer simply diffuses the attack and subsequently shrugs off Natsu's Lightning Fire Dragon Mode spell before pushing the Fire Dragon Slayer back, and sitting on his throne again as if nothing happened. As the three Dragon Slayers reel from his power, Mard Geer comments he hasn't even gotten serious yet.

Mard Geer then attempts to contact Kyôka, but finds that she is too engrossed in her battle with Erza. Deciding to leave her be, he answers Sting's question regarding the extinction of Magic, which he explains they're doing so that they'll be able to destroy the seal placed on E N D's book, which is composed of Magic Power, and return to Zeref's side. Inquired as to what that means, Mard Geer explains that written in their genetic code is the desire to reunite with Zeref, which he reveals is Zeref's way to finally day: he created the Etherious so that they could ultimately kill him. Adding that when E N D is revived they can kill Zeref, Mard Geer responds to Sting's complaint of human endangerment by calling humanity weeds in their path to their creator. Mard Geer then whips his opponents away with his Prison Flower, but it, along with his arm, is frozen by Gray's Ice Devil Slayer Magic. Stunned, Mard Geer asks exactly who Gray is and is shocked to learn that he's a Devil Slayer.

Mard Geer is then attacked by Gray and recognizes Silver's Magic, stating that he always knew the man would betray him, but remarks that the way in which he was betrayed is fascinating. Attacking Gray, Mard Geer's thorns are frozen almost immediately and he hit with a blast of ice. Subject to Gray's rage, a potentially fatal blow is stopped by a demonic Jiemma, which delights Mard Geer; after Jiemma reveals to everyone that he chose to be remade into a Demon, Mard Geer makes a claim that his power far surpasses the Nine Demon Gates' own. Smirking at Jiemma's threat to his life, Mard Geer says that the adjustments to Jiemma's emotions were a failure. As his wounds heal, Mard Geer asks Gray if he believes his newfound power will work when he releases his true form and states that he, like E.N.D. will truly awaken after a long period of time; entering his Etherious Form, Mard Geer reveals his true name, Mard Geer Tartaros, and states that they can call him the Underworld King; the definitive Demon. He then tells Natsu and Gray to step forth, calling their battle the final one.

Beginning, Mard Geer spreads his new wings and summons a large number of very thick, dangerous thorns which are immediately burned and frozen by Natsu and Gray, respectively. However, the Underworld King immediately appears above the two Fairy Tail Mages and grabs them by their heads before soaring upwards; as he does so, he grinds the two Mages' faces off of the concrete structures that surround him, telling them that on the other side of Tartaros lies punishment for those that transgress against Demons, and that he's going to grind everything of theirs (even their emotions) away. However, before long, Gray and Natsu begin to resist and free themselves before ultimately punching Mard Geer into the stone he was trying to kill them with. Mard Geer, however, takes little damage from the attack and recovers swiftly, continuously dodging Gray and Natsu's following attacks and replying with his own. Gray responds by making a tower of ice, and an unsuspecting Mard Geer is then hit full on by Natsu, who was hiding inside; however, Mard Geer once again shrugs the attack off as Gray and Natsu question his incredible strength. Hearing them, Mard Geer explains that he will always come out on top in terms of ability due to his use of a Curse, which, as an original branch of power from the One Magic, is far superior to Magic. When Natsu refuses to agree, Mard Geer begins to cast a Curse, creating black tendrils of energy that begin to wrap around and paralyse the two Fairy Tail Mages. The Demon tells them that he is going to use his greatest Curse on them: Memento Mori; the very attack he planned to defeat Zeref with. Gray and Natsu are caught up in the Curse as Mard Geer tells them that they will become part of nothing—neither the living nor the dead. With the Curse complete and Natsu and Gray having vanished, Mard Geer returns to his human form and prepares for Face to fire so that E N D can be revived.

Although he smirks at his apparent victory, Mard Geer quickly becomes furious at the two Slayers' survival, calling it impossible and pondering if they survived because of Silver's borrowed power. However, as Gray falls and he is left facing Natsu, Mard Geer's anger takes hold and once again enters his Etherious Form and rushes at his Dragon Slayer foe, though he is punched away rather quickly. Wondering what power Natsu is using as he is repeatedly beaten around, Mard Geer expresses utter shock when he realizes that Natsu has entered Dragon Force and his hit by the young man's Crimson Lotus: Phoenix Blade; he survives, albeit wounded, and angrily tells Natsu that he needs to do better to kill him before attempting to do the same back to him. As this occurs, Gray rises and hits Mard Geer with his own Ice Devil's Zeroth Destruction Bow and critically wounds him. Falling, defeated, Mard Geer telepathically communicates with Kyôka regarding Face, to which she tells him to not fear, as it has activated and Magic Power is going to disappear from the world.

Forced to exit his Etherious Form upon defeat, Mard Geer falls to the ground, defeated and mortified. Shortly thereafter, after Face activates, Mard Geer regains his composure and tells Gray and Natsu that everything is just beginning, and that Magic Power will disappear and Curse Power will reign, as well as that when E N D revives, humans will not have the power to resist his will. However, when a heavily wounded Scavenger falls from the sky and Igneel stands upon his body, Mard Geer loses his cool and begins to panic when the Fire Dragon King reveals that more Dragons have arrived and are destroying Face as he speaks. His panic then turns to utter shock as Zeref also arrives on the scene, having come to take back the Book of E N D for himself. Despite still being floored due to his previous fight, Mard Geer begins to plead with Zeref and tries to tell the Dark Mage that he can still help him realize his goals. Albeit praising Mard Geer on almost reviving E N D, Zeref states that he has no more use for the Demon, and, with a click of his fingers, defects Mard Geer from the Books of Zeref, sent back to the Underworld, and destroyed the book he was summoned from.

Alvarez Empire Arc
Mard Geer returns from the Underworld and creates the Reborn Tartaros to steal the Book of E N D and revive him. Mard soon sees Kyle Afdéderk fighting off his Edolas counter-part; Kyle Scavenger. He is in shock to see Kyle because he defeated Mard and Tartaros way far back enraged when Mard killed his daughter, Wendy Marvell. Mard sees black Face(s) all around and thinks that Kyle created them to make 50% of the world Curse power and the other made out of Magic.

The Dark Face(s) activate and set off a huge explosion causing the seal on the Book of E N D to break. Forcing the book to break, Natsu is seemed to be "transforming" into his True Form; Etherious Natsu Dragneel. Mard is seem in shock when he almost killed Natsu a year ago at Cube's ruins. Albeit to that, Lisanna Strauss sees Natsu beg in mercy to die, and so kills him in one blow.

Mard then challenges off Kyle to a duel to the death, until the God of Life and Death, Ankhseram, shows himself in Physical Forme and starts to drain the Mage's and Etherious's power. Rather than that, Mard releases Memento Mori and takes critical damage from the God's Magic. Soon the Mage overpowers both and defeats Mard Geer, then sends him into a portal back to the Underworld.

Underworld Arc
Mard Geer Tartaros is seemed to be at war against Exorcist Mages in the Underworld. An artificial Etherious and the Dragon King were sent to the Underworld to end the Human-Demon Civil War with a peace treaty and kill the Underworld King. Mard vowed revenge against the Dragon King, so it would be the time of the final battle, Dragon King Vs. Underworld King.

War led to a stalemate and was nowhere near to signing the peace treaty. The Dragon King and Underworld King were at war that it led to The Thousand Year Gap. The Underworld King began to gloat that all humans are weak and will die. Until, the Dragon King threatens that E N D is on his side which brings him to shock because he was killed. The Dragon King claims that he used Revival to give his brother a third chance in life.

During shock, Mard Geer asks for death once and for all for he is struck in fear and he realizes his actions were pitiful. The Dragon King leaves him to die in guilt and fear for the Ultimate Death and returns to Fiore with E N D and the Exorcist Mages. Months later, Mard suffers the Ultimate Death and turns into nothing.