WARNING: The following contains spoilers for Season 5 of The Seven Deadly Sins, now streaming on Netflix.
In The Seven Deadly Sins' lore, an ancient rivalry between the Demon and Goddess Clans brought about a Holy War, which spilled over into the human world. Beginning over 3,000 years ago, Season 4 detailed how the Holy War was eventually brought to a halt by the demon mage Gowther until it was reignited in the current storyline. But the way Gowther brought the war to an end was never explained --until Season 5's release.
How The Seven Deadly Sins' Holy War Really Ended
Episode 4 of The Seven Deadly Sins' fifth season, "The Victims of the Holy War," finds Ban, Meliodas and Wild facing off against the Demon King in Purgatory. Suddenly Meliodas notices that his memories of his middle brother Esterossa have suddenly vanished, something the Demon King notes he is also experiencing. The scene shifts to the fight between Sariel, Tarmiel and the remaining Sins against Esterossa as he attempts to absorb four of the Commandments for the first time in Season 5. Gowther looks on at the battle as Sariel and Tarmiel become confused as well.
In a flashback, two Gowthers -- the original and his doll -- overlook a burning forest. The original Gowther, a powerful demon mage, lets his doll know that he plans to end the Holy War by casting a forbidden spell. The scene shifts once again, and this time it's Elizabeth’s memory. She remembers a conversation she had with Meliodas about his little brother Zeldris, in which Meliodas comments that Zeldris is his only brother.
Back in the real world, a cocoon surrounds Esterossa, and after a gust of wind, it hardens and crumbles away. As the figure inside emerges, Hawk questions Gowther about the situation. Gowther explains the forbidden spell from 3,000 years ago has been lifted. The man known as Esterossa was, in truth, the fourth Archangel, Mael.
As it turns out, because Meliodas had betrayed the Demon Clan, the Goddess Clan gained the upper hand in the Holy War. Not wanting the extinction of his people, he used the forbidden spell to make Mael, a Goddess equal in power to Meliodas, believe himself to be Esterossa. Because the Goddess Clan lost their most powerful warrior, they chose to seal the Demon Clan as opposed to genocide.
Meliodas & Mael's Connection
The similarities between Meliodas and Mael don't end with just their power level. Much like Meliodas, Mael was in love with Elizabeth. This highlights one of the series protagonist’s most significant flaws: his selfishness. Unlike most shonen protagonists, Meliodas’ motives have little to do with helping others, as his only goal is to be with Elizabeth. This seemingly simple goal has had massive ramifications throughout the series, even affecting Elizabeth herself as she was cursed with reincarnation by the supreme deity.
Now, as a direct result, Meliodas essentially forced Mael to take his place, sealed within the Coffin of Eternal Darkness, while also stealing the one he loved. But it gets worse. In Season 5, Episode 5, "The Tragic Strike," Mael becomes frantic as he begins to remember his life as Esterossa. Not only was he sealed away for 3,000 years, but he committed many atrocities due to his personality being altered.
Meliodas’ choice had forced a fate worse than death upon Mael and essentially switched their roles within the series. As a member of the Demon Clan, Meliodas himself was originally a brutal killer, inspiring many of his kin with his prowess on the battlefield. Yet, due to his selfish desire to be with a member of the Goddess Clan, he abandoned his clansmen, forcing Gowther to corrupt Mael. If Meliodas had remained with the Demon Clan, not only could both he and Elizabeth’s curses have been avoided, but Mael would likely have had the opportunity to serve as the hero of the story.
Is Meliodas' Demon King Fate Still Sealed?
Enraged at his unfair treatment, Mael continued to absorb the four Commandments, as he needed power in the absence of his Grace, Sunshine. Due to his incompatibility with the Commandments, as he is a member of the Goddess Clan, Mael began to go on a rampage, his mind consumed by the Commandments.
However, Season 5, Episode 7, "Hope, Conflict, and Despair," reveals that Gowther chose to corrupt Mael because he had killed Gowther’s lover Glariza. Upon hearing this from Gowther, Mael began to return to his senses, understanding he was not entirely innocent.
As Mael returned to himself, he once again donned the persona of a virtuous warrior, pledging to help the Sins in the battle against the Demon Clan. Despite the battle being hard-fought, the Sins gained a powerful ally as a result. But whether it'll be enough to stop Meliodas from becoming the Demon King remains to be seen in The Seven Deadly Sins.