Demon Clan

The Demon Clan is one of the five major races in the world of Nanatsu no Taizai.

Overview
Three thousand years ago, the Demon Clan constantly clashed with the Goddess Clan. Their elite group of warriors are the Ten Commandments, who were handpicked by the Demon King due to their power. Many demons consider themselves above those of other races for their great power, especially humans. However, the two legendary clans were largely evenly matched and thus a tentative balance was created. At some point in time, the Goddess Clan broke a treaty with them, and even slaughtered many women and children they were holding as prisoners of war.

At some point, the Vampires became allies yet subservients to the Demon Clan. When the leader of the Commandments, Meliodas, betrayed his own people for his alliance and relationship with the powerful goddess, Elizabeth, and severely crippled their strength by killing two members of the Ten Commandments when escaping, it indirectly caused two events: The rest of the goddesses seized the opportunity to defeat the Demon Clan, who waged a great war against the Goddess Clan, who had allied with the Giant Clan, Fairy Clan and humans. The Vampire Clan decided to rebel during this time as the Demon Clan got weaker, but still got single-handedly defeated.

As a result, the Demon Clan was ultimately defeated by the Goddess Clan and their allied clans, being sealed away in the Coffin of Eternal Darkness for many years. In spite of their fate though, a few demons managed to escape from or avoid the seal completely, namely the Red Demon, Gray Demon and Fraudrin. The latter would spend sixteen years trying to find a way to break the seal and to resurrect his clan, so they could take over the land of Britannia.

The other nine members of the Commandments were eventually resurrected when Hendrickson manages to break the seal in present day. Their biggest threat on their way to conquer the country once more turns out to be a member of their own race; Meliodas, their previous leader and the oldest son and heir of the Demon King, who was still alive thanks to his father's Inmortality Curse.​

After organizing a fighting festival to lure Meliodas into a trap, they managed to kill him and begin the conquest of Britannia in the following month, taking the soul of every human they come across in order to regain their strength. However, when the Ten Commandments tries to conquer the kingdom of Liones, they are eventually stopped by the group formed with the goal of destroying them, the Seven Deadly Sins, as well as Meliodas, who has revived thanks to the curse that the Demon King put on him.

The remaining members of the Ten Commandments, Zeldris and Estarossa, took refuge in their established base in the kingdom of Camelot, where they sacrificed human souls in order to completely break the seal and liberate the entire Demon Clan. Eventually, the fearsome Cusack and Chandler joins them, as did Meliodas, who had decided to become the new Demon King to break the curse on him and  Elizabeth.

When the Four Archangels of the Goddess Clan revive to join Elizabeth, the Seven Deadly Sins and the humans against them, the Demon Clan faces a new Holy War.

Appearance
Many of the Demon Clan have monstrous appearances. There are several known types, each with its own appearance, identified by colors, such as Red Demons or Gray Demons.

However, at least some demons do not fall into these categories, namely the Ten Commandments and Meliodas. Human-like demons can be distinguished by their pitch black eyes.

Physiology
Unlike humans, Demons have more than one heart. The number of hearts varies, although upper-level demons have seven hearts. The removal or destruction of a single heart does not incur death, although it is painful. Destroying all their hearts, regardless of their strength, will kill them.

Some demons have black markings on their face, which vary from demon to demon. Because of its many uses, many demons find it convenient to keep their bodies or weapons cloaked in darkness constantly to various degrees, Demons that do such include members of the Ten Commandments Grayroad, Melascula, Derieri and Monspeet, as well as the highest-ranking demon Cusack.

Drinking the blood of a demon may give non-demons enhanced strength and magical power, if they are compatible. If they are not, they will explode. Demonic blood may naturally or forcibly turn the drinker into a demon themselves, a process that can be reversed either by removing their demonic plant or through the power of the goddesses.

Powers and Abilities
The Demon Clan is an extremely powerful race, only being on equal on power with the goddesses and being sealed by the cooperation of the latter with fairies, giants and humans. According to Chandler, a demon's power is at least two-fold greater at night.

Members of the Demon Clan share several common abilities:
 * Power of Darkness: Demons can create and manipulate a mysterious dark substance to enhance both their offensive and defensive abilities. It has been shown to form various weapons and to protect them from attacks that would otherwise cause serious injury. It can also be morphed into various shapes.
 * Enhanced Regeneration: They can use their darkness to piece together an injured demon's body and mend grave wounds, but are unable to regenerate destroyed hearts and any damage sustained accumulates unless one of them are similar to an immortal.
 * A powerful, dark flame that never extinguish and is capable of negating regenerative abilities. It also can be invoked in the form of an enchantment.
 * Soul Stealing: Demons are capable of forcing the souls of living creatures (even other demons) out of their bodies either by chanting an ancient spell to do so in mass or by simply touching the person whose soul they wish to take. Eating these souls allows them to replenish their magic and also gives them access to the person's memories, but will cause that soul to die.
 * Indura Transformation: A secret taboo skill, only known to and allowed for a few of the highest ranked demons, such as the Ten Commandments. The user makes a contract by sacrificing six of their seven hearts, their original form, and ability to reason in exchange for great power. It can only be performed by upper-level demons, and one must have a power level of greater than 50,000 in order to perform the technique without dying. Once transformed, the Indura will not stop until every last bit of its life force has been used up.
 * Demon Control: Higher ranked clan members such as Chandler, Cusack, Zeldris, Gloxinia and Monspeet are shown to be able to command lower ranked demons into doing their bidding.
 * Flight: They may also use their own darkness to form wings, helicopter like blades, or simply for levitation, allowing them to fly.
 * Possession: According to Sariel, high-ranked Demons, like Goddesses, are able to take human bodies as vessels and use them as their own, being able to use all their abilities through this method. However, the vessel may have difficulty hosting these Demons, leading their bodies to undergo transformations.