Demon King

The is the king of the Demon Clan. He is the one who handpicked the Ten Commandments and granted them their Commandments. He is also the father of Meliodas, Estarossa, and Zeldris, three of the most powerful members of the Ten Commandments.

Appearance
The Demon King is shadowed in his first appearance, towering over Meliodas. In his first full appearance he is seen as an enormous armor-clad man whose height reaches the clouds. He wears a long partially torn cape and wields a massive sword. He also has a horned helmet and a full long curly beard.

Personality
The Demon King is fully devoted to the Demon Clan and he seems to put power and evil above all else, chastising Meliodas for throwing away his former life just for the sake of a woman. He is also very serious in matters that involve the Demon Clan but is neverthless not without a dark and sarcastic sense of humor, as evidenced when he clearly taunted and mocked Meliodas. He has no empathy for demons who go against the laws of the Demon Clan, even if it is his own son, evidenced when he ruthlessly killed and cursed Meliodas for betraying the Demon Clan and loving Elizabeth. When he makes up his mind, he will hear no objection from his subjects, even his own children, as not even Zeldris dared to disobey the Demon King when he told him he will made Meliodas the new ruler of the Demon Clan. However, despite his ruthlessly strict and harsh judgement, the Demon King is not completely unforgiving and without mercy, at least when it came to Meliodas, his first, strongest and favored child, as while he was hostile and even mocking towards his traitorous son when he was in Purgatory, the Demon King was fully willing to crown Meliodas as the New Demon King when he had returned to his old self and was visibly pleased when Meliodas had reverted him back to his old self. Cusack even said The Demon King was being far too compassionate with Meliodas and even noted he did this because he still considers Meliodas as his son despite their currently mutually antagonistic relationship.

The Demon King is shown to be considerably calculating and intelligent, as evidenced by his quickly realising that giving just a single Demon half of his power would mean threatening his rule and thus choosing to divide his power into 10 pieces to make sure he can still rule the vast and chaotic Demon World without allowing any challenge to his rule. It is also noted that the Demon King is unpredictable, even to his sons, as Zeldris noted he can never know what his father is thinking.

History
Little of the Demon King's past is known. However, he would become the ruler of the Demon Clan and due to the Demon World being so chaotic and vast at his rule, the Demon King at first considered giving half of his power to his servant, but that choice was out of option as it could threaten his reign. As such, to avoid giving too much power to someone, the Demon King chose to divide his power into ten pieces and gave it to the Demon Clan warriors he found worthy, thus creating the Ten Commandments.

3,000 years ago
After the betrayal of his son Meliodas and the death to the hand of two of the Ten Commandments, the Demon Clan entered the war with the Goddess Clan, who allied with the Human, Fairy and Giant Clan, thus unleashing the Holy War.

Having heard about a girl from Belialuin who possessed infinite magic, the Demon King dealt with her at the same time as the Supreme Deity in order to put the girl on his side. When the girl told them that she would follow the one who gave her the best blessing, the Demon King gave her all the knowledge of the magic of the Demon Kingdom as well as immunity to the possession and brainwashing of the Goddesses. However, being deceived by the girl who rejected them both taking their blessings, the Demon King and the Supreme Deity destroyed Beliauin in their anger.

During the last few days of the Holy War, he and the Supreme Deity having lost their patience in their shared anger and having had enough of their children's repeated defiance of the laws of their respective clans worked together and fought against Meliodas and Elizabeth, effortlessly killing them and cursing them for eternity. The Demon King cursed Meliodas with immortality as his punishment, reviving him every time he died, in exchange for his emotions being consumed more and more to the point of returning to be the bloodthirsty demon he once was.

Eventually, he, alongside the other members of the Demon Clan, were sealed away after losing the Holy War.

Defensive Battle for Liones arc
After Meliodas's fight with the Ten Commandments, the Demon King greets him in Purgatory. He admits to having been keeping an eye on the captain of the Seven Deadly Sins throughout and muses that even Meliodas was unable to do anything other than wait for death when caught by the Commandments of Piety and Love. When Meliodas counters that he is now free from the Commandments' bindings thanks to his curse, the Demon King agrees but mentions that he can feel Meliodas' quivering. Entertaining Meliodas' bluffs, he expresses anger towards the certain woman who had changed Meliodas 3,000 years ago and then informs him that though he was left in a greatly weakened state, the curse he casted on the Dragon's Sin of Wrath would allow him to feed on his emotions every time he dies, allowing the Demon King to regain his lost power and at the same time reverting his traitorous son back to the state he was three thousand years ago. He is then attacked by an outraged Meliodas.

Prelude to the New Holy War arc
After Meliodas fight with Escanor, the Demon King senses that his son has started to return to his former self, much to his delight. He contacts his youngest son and representative, Zeldris, and shows no interest when Zeldris expresses he will find the one who killed the demons guarding Camelot, instead telling Zeldris that while his seal is not yet broken, Meliodas will now replace him as the rightful heir to the throne of the demon king. Despite Zeldris obvious shock and visible anger and discontent, the Demon King casually orders Zeldris to retrieve Meliodas and crown him as the new demon king.

Abilities and Equipment
As the ruler of the Demon Clan, he is terrifyingly powerful and strong, as he is certainly the strongest and most powerful demon. Evidence of his power was that just possessing a fraction of his power made the Ten Commandments among the strongest demons in existence. All three of his sons also inherited a portion of his strength, which was sufficient to make them the strongest members of the Ten commandments. While he rarely fights, the Demon King also possesses terrifying skill and might in battle, as he proved capable of easily overpowering and killing and cursing Meliodas, the former leader of the Ten Commandments who was greatly feared by enemies of the Demon Clan when he was still in the side of the Demons, when he decided to finally punish his oldest son for his repeated defiance of the Demon Clan and being in love with Elizabeth. According to Meliodas when saying on how to lift the curse on him and Elizabeth, which can only be done by someone as equally powerful as the Demon King, the Supreme Deity is the only being whose level of power is equivalent to the Demon King's. Zeldris and Meliodas also says that even with the power Zeldris borrowed from the Demon King added to Zeldris's own, it still pales compared to the Demon King's true level of power and Meliodas also said that even his full power augmented by the power that Zeldris borrowed from their father cannot rival the Demon King's true power nor can he reach the Demon King's level of power by training and the only way for him to be able to gain power equal to that of the Demon King being to absorb all the Ten Commandments into himself, as the Commandments are fragments of half of the Demon King's power.

The Demon King is exceptionally powerful in the use of curses and blessings, having been the one that created the unique but extremely powerful curses of the Commandments that the Ten Commandments wield. He is also the one who created and cast the unique and permanent curse of immortality on Meliodas that is so powerful it can only be lifted by the King himself and the Supreme Deity, or someone as powerful as both gods. He can grant an individual with immunity to the brainwashing powers of the Goddess Clan and all the secret techniques of the Demon Clan. Alongside the Supreme Deity, the Demon King created a fog of death with fire and lightning capable of killing all the inhabitants of Bellaulin.

The Demon King is also capable of lending a portion of his power to others, as he did with Zeldris when Zeldris became his representative. He has the abillity to telepathically communicate with his youngest son and representative Zeldris even despite being sealed in Purgatory. He can also turn members of other species to demons and grant them the powers of one were they to make a pact with him, as he was able to transform Gloxinia and Drole from being a Fairy and Giant to a Demon when they chose to become a member of the Ten Commandments.

Abilities

 * The Demon King is capable of bestowing a Commandment on those he deems worthy. These Commandments are a fraction of the power of the Demon King himself and deliver a unique curse to whomever breaks a rule specific to each Commandment as well as increases the power of whoever is wielding them and if they were to be bestowed to individuals of a species diffrent from Demons, the Commandments would turn them into Demons as well. This power is absolute; it cannot be opposed even by its wielder, only those who also possess a Commandment are immune. The curses will only be lifted if the victim defeats its wielder or at the victim's death. Notably, these curses are not magical in origin, activating even when their holders are drained of magic, and are perceived differently than magic is as well. The Commandments can be withdrawn from their wielder if he gives his consent, or if he is powerless, unable to fight or die with Admonition.
 * Those who show faithlessness in the holder's presence will have their eyes set ablaze. It is held by Melascula.
 * Those who stand before the Commandment holder with hatred in their hearts will be rendered powerless to harm or inflict damage on anyone else. It is held by Estarossa.
 * Any who kills in the holder's presence will have their own time stolen from them, causing the victim to age rapidly and die. It is held by Grayroad.
 * The curse and its activation are unknown. It was held by Drole.
 * Any who turn their back to the Commandment's holder are treated as committing an act of treachery, and are cursed into serving the Demon King, and by extension the holder who is acting as the Demon King's representative. It was once held by Calmadios, and is currently held by Zeldris.
 * The curse and its activation are unknown. It is held by Derieri.
 * The curse and its activation are unknown. It was held by Gloxinia.
 * The curse and its activation are unknown. It is held by Monspeet.
 * Those harboring greed, avarice and desire will be inflicted by its curse will lose their memories, feelings, and entire sense of self. It was once held by Gowther, but was later passed on to Fraudrin upon Gowther's disappearance.
 * This Commandment determines that any who tell a lie in the holder's presence will be turned to stone. However, only those who are aware that they are lying will be affected. It is held by Galand.


 * Immortality Curse: The Demon King is capable of casting an incredibly powerful curse that revives the victim without fail regardless of the means of death, including suicide or getting killed, no matter how many times they die. It additionally prevents the victim from dying of old age. In exchange for the infinite number of revivals, the victim's emotions are slowly drained to nourish the King. The only way to dispel the curse is to get a power equivalent to the King himself or the Supreme Deity and aside from the Demon King and the Supreme Deity themselves, the only known being who can remove it is the one who possess all the 10 Commandments. The only known victim of the curse is Meliodas.

Weapons

 * Large Boardsword: When he teamed up with the Supreme Deity to punish their children for defying the laws of their respective clans, the Demon King is shown to wield an enormous boardsword with a curved tip in similar concept to the large boardsword Meliodas wielded 3,000 years ago. It's safe to assume he is exceptionally capable with the sword.

Meliodas
The Demon King was once apparently fond and proud of Meliodas due to Meliodas's surpassing power and skill and acknowledged his power and also he considered Meliodas to be the most worthy and only heir to the throne. However, their relationship became very strained when Meliodas betrayed the Demon Clan, as the Demon King was extremely angry for his betrayal, which caused the King to lose his worthy heir. As Meliodas continues to relentlessly defy the Demon Clan and the laws of his clan, their resentment for each other soon escalates to the point that the Demon King had no qualms killing his son and cursing him with Immortality to forever seperate him from Elizabeth and punish him for his defiance, something that made Meliodas strongly despise him, resulting in their extremely antagonistic relationship being mutual. Even centuries after, the Demon King and Meliodas's grudge and resentment for each other remained as strong as ever, evidenced when they both mock and taunt each other after Meliodas was briefly killed by Estarossa and descended to Purgatory. However, despite all that happened between them, the Demon King still considers Meliodas to be his son and the rightful heir to his mantle and throne and appears to be willing to fully dismiss Meliodas's former betrayal should he ever return, as evidenced when he openly revels in the idea of bringing his oldest son back to the fold and after Meliodas fell back into his former self, the Demon King was delighted and immediately ordered Zeldris to retrieve his elder son and crown him the new king of the demons, completely disregarding his son's betrayal and Zeldris' visible discontent and shock, even going as far as to chatisise Zeldris for his antagonistic reaction to his decision and sternly making it clear that he will not hear any objection of Meliodas's rule.

Zeldris
He and Zeldris have a fairly good relationship. The Demon King gave Zeldris his power to use and Zeldris appears to respect his father greatly, immediately apologizing for having The Demon Clan embarassed at his command and promising to find and kill the one who humiliated them. However, the Demon king is also not afraid to be firm to Zeldris and seems to be disregarding of Zeldris's feelings and ambition, as he was able to silence his youngest son quite casually when he questioned his order to rescue Meliodas, despite knowing that Zeldris resents Meliodas and wants the throne for himself. Neverthless, Zeldris is fully loyal to his father, as he, albeit very begrudgingly, obeyed when The Demon King ordered him to crown Meliodas as the next King of the Demons.

Estarossa
The Demon King took pity on Estarossa as he is unable to be on par with the rest of his children in magic and power when it is revealed that Estarossa was born without the ability to manipulate darkness, which is supposedly an innate ability of demons. The Demon King decided to instead give Estarossa a Commandment, to hopefully awaken the darkness in his second son, however the plan backfired when Estarossa was left mentally unstable. Estarossa holds less respect for him compared to Zeldris', calling him the "old man" rather than father when he learned the Demon King still ordered Meliodas to be retrieved and crowned as the King of the Demons.

Supreme Deity
Despite being mutual enemies from leaders of opposing clans, the Demon King teamed up the Supreme Deity to punish their children during the Holy War for their continued defiance to the laws of their respective clans, showing that they are capable of working together when the situation demands it.

Elizabeth
The Demon King has a strong resentment and hatred for Elizabeth as she is why Meliodas, his heir, betrayed the Demon Clan. He evidently took sadistic pleasure in seeing Elizabeth cursed and unable to be with Meliodas.

Memories of the Holy War arc

 * Meliodas and Elizabeth vs. Demon King and Supreme Deity: Win

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