The Seven Deadly Sins anime and manga feature its namesake -- themes traditionally used to highlight traits that all humanity exhibits -- through Meliodas' Holy Knights. He and his Seven Deadly Sins are regarded as the strongest Order of Knights in the Kingdom of Liones. They consist of seven individuals found guilty of committing a heinous crime against morals and have since been branded with a sin.
By exploring each sin's definition more abstractly, the series takes the idea of the Seven Sins to another level. The Seven Deadly Sins even going as far as to showcase how not every character may be guilty of their Sin in the way that we'd expect -- or if they're directly at fault at all.
Meliodas (Dragon's Sin of Wrath)
Despite being named for wrath, Meliodas appears as a typically relaxed and carefree protagonist even under extreme circumstances. However, we later find out that he is prone to angry outbursts from time to time, especially per his demonic powers -- which he represses to prevent destruction.
This destructive, demonic power -- and the reason Meliodas tries to contain it -- is seen when he is forced to watch the love of his life, Liz, die before him. Overcome by grief, he loses himself to anger and consequentially destroys the Kingdom of Danafor. Though occurring under a moment of great heartache and loss, Meliodas's display of tremendous wrath wiped out an entire Kingdom, thus earning him his Sin.
Diane (Serpent's Sin of Envy)
A member of the Giant clan, Diane consistently showed envy towards humans due to their small size. She is also envious of Elizabeth for some time due to the attention she receives from Meliodas.
One day, Diane and her mentor, Matrona, a warrior leader to the Giant clan, are hired as mercenaries by the Kingdom of Liones. Unfortunately, the job is a trap meant to kill Matrona, who some think poses a threat to the kingdom. The attackers managed to strike Matrona with a poisonous spear as she tries to protect Diane. Despite her injury, Matrona murders a majority of the Knights before succumbing to the poison. Deeply saddened by Matrona's death, Diane was then captured by the remaining Knights and sentenced to capital punishment under the pretense of killing the Knights and Matrona out of envy.
Ban (Fox's Sin of Greed)
Ban displays greed in his day-to-day life, hoarding material possessions and even stealing stuffed animals from children simply because he can. Though his selfish desire also extends to his obsession with bringing his lover Elaine back from the dead. This greed sometimes gets the best of him as he even attacks Meliodas -- his best friend -- in an attempt to bring her back.
He had once traveled to the Fairy King's Forest to drink from the Fountain of Youth to gain immortality. However, Ban gives up when Elaine -- the forest's guardian -- explains that the fountain keeps the forest alive. Unfortunately, the Red Demon attacks the forest, fatally wounding both Ban and Elaine. In Elaine's final moments, she gives Ban water from the Fountain of Youth, saving him. As the only survivor of the destruction, the blame for burning the forest and killing Elaine lands on Ban. He bears the Sin of Greed as it's presumed he did these acts for personal immortality.
King (Grizzly's Sin of Sloth)
Named for Sloth, the Fairy King demonstrates his laziness frequently by choosing to levitate instead of walking. Additionally, his sacred treasure often takes the form of a comfortable pillow for him to rest on. Plus, his fighting style usually consists of him staying in one place as he lackadaisically releases his power.
When humans were attacking the Fairies, King leaves the forest to save them but is knocked off a cliff by Aldrich, a Holy Knight. Luckily King survives, but unfortunately, he loses his memories. As such, King was unaware of everything in the Fairy World until he regains his memories 500 years later. In his absence, his friend, Helbram, raised a calamity against the humans, thinking they had killed King. Accused of neglecting his duties as the Fairy King, which eventually led to the forest's destruction, King must bear the Sin of Sloth.
Gowther (Goat's Sin of Lust)
While lust is often perceived as the sexual desire felt towards a person, it is more accurately a desire felt towards something, hence the phrases "lust for power" and "lust for money." While not displaying a sexual desire for any person, Gowther frequently desires to understand human emotion, going to great lengths to do so since he is a doll created by a wizard.
Later, it is revealed that Gowther used to possess a heart. He fell in love with Princess Nadja, who was terminally ill, and she, in turn, loved him back. Nadja later dies in Gowther's arms, where he tries to give her his artificial heart in a vain attempt to save her. Caught by guards at this moment, Gowther was accused of seducing, assaulting, then murdering the Princess. For that, he was sentenced to death and named the Sin of Lust.
Merlin (Boar's Sin of Gluttony)
Often used about food, gluttony is the over-indulgence or consumption of things. Being a mage, Merlin is obsessed with attaining knowledge and, as an extension, power, making questionable choices merely to study and learn. This trait is evident in the story as she treats people as tools for her experiments, even referring to them as "guinea pigs."
Merlin was deemed "miraculous," born with infinite magic, a compelling and sought-after power. When two Gods, the Supreme Deity and Demon King, showed interest in recruiting Merlin into one of their clans, she deceived both of them in her desire to obtain knowledge and power. Consequently, the Gods attacked her homeland, Belialuin, for 1000 days, annihilating the town and leaving Merlin as the only survivor. Blamed for the destruction of Belialuin, she was named the Sin of Gluttony.
Escanor (Lion's Sin of Pride)
While portrayed as a shy, feeble bartender at night, during the day in the light of the sun, Escanor's physical and mental state changes drastically, and he transforms into a large, muscular man. In this state, he possesses immense power and is known as "The Strongest Holy Knight." In this form, he becomes extremely arrogant in his abilities and has no problems showing off his fearsome might.
Escanor once rid Liones of a demon who was rampaging in a town. However, he could not fully contain his incredible power, and many Holy Knights were injured in the process. He was eventually restrained as the people grew terrified of him and his abilities. When he reverted into his polite nighttime form, he tried to explain that he was well-intentioned but had no evidence to prove it and, for his attitude, was assigned the Sin of Pride.