Meliodas is a demon that has lived for thousands of years. Many years in the past, he lived in the Kingdom of Danafor, and was even a knight there. However, when his lover Liz was killed, Meliodas' wrath consumed him and he destroyed the entire kingdom in a rage. After that, Meliodas formed the Seven Deadly Sins, a group of seven criminals who would serve as knights under Meliodas' leadership. Unfortunately, the Sins were framed for the murder of the knights' grandmaster and were forced to go on the run, Meliodas going into hiding and opening up a bar. One day, the princess of the kingdom, Elizabeth, came into Meliodas' bar in hopes of finding the Seven Deadly Sins and stopping a plot by the knights to send the kingdom into war. Meliodas revealed himself to Elizabeth as the group's leader and agreed to help her find the other Sins.
Superhuman Physicality: As a demon, Meliodas is much stronger, faster, and tougher than most humans.
Full Counter: Meliodas' signature ability, Full Counter lets him reflect an attack sent at him back at their user with added power.
Counter Vanish: A variation of Full Counter that dispels energy attacks instead of reflecting them.
Revenge Counter: Meliodas' strongest technique, Revenge Counter turns off Meliodas' abilities so he can soak up damage before he pours all the power from the attacks into his sword and unleashes an extremely powerful attack onto his opponent.
Enchantment: Hellblaze: An enchantment that lets Meliodas conjure and control demonic black flames that are very hard to put out and nullify regeneration. Meliodas can imbue Hellblaze into his fists, feet, and weapons to increase their power.
Kami Chigiri: Meliodas raises his power and concentration to their limit before covering his weapon in black flames and swinging it, releasing a powerful wave of black fire
Dragon Handle: A broken sword that Meliodas uses in fights to hold back his full power. In reality, the hilt is a key to releasing the sealed Demon Clan, and it can be used to project illusions of a dragon to scare enemies.
Liz's Sword: A sword given to Meliodas by his late lover, Liz. While it's a normal sword, Meliodas' skill makes him very dangerous while wielding it.
Lostvayne: Meliodas' Sacred Treasure, a magical weapon that draws out his full power while he uses it. When he wields it, Meliodas can use Physical Clone to create up to four copies of himself. While the clones have only half of his power, which splits with each new clone made, each of them can use Full Counter to reflect four attacks at once.
Demon Form: When Meliodas gets angry enough, he can tap into his demonic powers, forming a black mark on his forehead and giving him a boost to his strength, speed, and durability. As he gets angrier, the black mark spreads until it covers more and more of his body, his power increasing as the mark spreads. When the mark spreads, Meliodas can manipulate the markings to form weapons, wings for flight, use it as armour, reattach lost limbs, and even fire it as a ranged blast of dark matter that can obliterate a whole kingdom at full power. However, the more the mark spreads, the more Meliodas starts acting on instinct instead of rational thought.
Full Counter has Flaws: Full Counter can't be used against ordinary punches and kicks, or indirect attacks, and Meliodas is unable to attack while using it.
Holds Back: Meliodas holds back a lot, mostly to avoid doing something like destroying Danafor again. He doesn't like to use his full demonic power, and will only use his demon powers in short bursts if he has to.
Demon Form Acts on Instinct: Meliodas' demon form has shown to act on instinct instead of strategy, but after regaining his full power, Meliodas seems to have overcome this.