Arthur Pendragon/Plot

Kingdom Infiltration arc
When the three Seven Deadly Sins - Meliodas, Ban and Gowther - invaded the Kingdom of Liones in order to save Elizabeth Liones, Arthur leads a sizable army of Holy Knights from Camelot. His presence is easily noticed by both Great Holy Knights and the three invading Deadly Sins. Outside of the castle, Arthur is seen riding his huge warhorse and stands with his assembled forces and a mysterious cloaked person beside him. When Hendrickson confronted Arthur outside of the gates with his two Holy Knights the king of Camelot wished to be granted audience with King Bartra soon after the cloaked individual removed their illusion of an army, revealing it to be a ruse just to get the Holy Knights' attention. Hendrickson lied to Arthur, saying the king was sick and was under care of the kingdom's finest mages but Arthur told the latter that his cloaked friend could heal the sickly king. Hendrickson refused Arthur's offer but the young king remained firm and would not leave because if there was a problem he would be helping.

Hendrickson reluctantly accepted Arthur's offer and escorted the king of Camelot and his cloaked friend to the castle. While on the way there, Hendrickson questioned Arthur if he knew of the problem they are facing only for the young king to reveal that he made it up, making the Great Holy Knight grew suspicious of him. Asking Arthur once more, this time of what he is after, which Arthur refused to reveal, Hendrickson and his two other Holy Knights surrounded the duo and told them that they killed every foreign messengers who visited Liones, even if he was the king. Then suddenly, Vivian appeared out of nowhere and informed Hendrickson of an event and teleported away. When Arthur asked if the female Holy Knight was a Liones mage, Hendrickson immediately attacked Arthur with one slash, telling him that he will not live to find out.

After sending the king of Camelot flying to a building, Hendrickson discovered that he received a cut on his head, realizing that Arthur's reputation was merely not for show as the latter blocked Hendrickson's attack with his sword while at the same time wounding him. Arthur then comments that Hendrickson is not bad being a Great Holy Knight as the king of Camelot prepares to battle him while his cloaked friend dealt with the other two Holy Knights. Arthur and Hendrickson's battle reaches the center of Liones as people left in fear of the two. Arthur told Hendrickson to finish their fight, while Hendrickson wonder at the young mans strengths and powers, but Arthur went toward Hendrickson and started attacking him with multiplied sword slashes while Hendrickson blocked all of them. Arthur told Hendrickson to stop holding back, while the latter asked Arthur to do the same, and show him the power that made Arthur the new king. Hendrickson sent Arthur crashing into the wall of a building and summoned Hellblaze to kill Arthur, while Arthur was fair and wondered about Hellblaze's ability. As an irritated Hendrickson used Hellblaze Scream, it was counter by Meliodas who appear in the scene between them as Arthur was alarmed by Meliodas' appearance.

Arthur watched in amazement at Meliodas's skill, but when Hendrickson mentioned that Meliodas is the captain of the Deadly Sins, Arthur joined the battle when Gilthunder appears and attacks Meliodas. Meliodas thanked him and asked him if he could give him a hand in the fight. He also asked him for his name, as Arthur told it to him, he also mentioned he had heard of him and knows him, and then they both prepared to face Gilthunder and Hendrickson together. When Hendrickson provoked Meliodas, leading to the Dragon's Sin of Wrath suddenly attacking two Holy Knights with full force pushing them back and slightly wounding them, Arthur was astonished. Witnessing Meliodas and Gilthunder clashing with great speed and skill, Arthur was shocked that the two combatants were not even serious in their battle, only for Hendrickson to swiftly appear behind Arthur to tell him that it is the same thing between them before resuming their battle. As Gilthunder used Iron Hammer of the Thunder Emperor on Meliodas close-range, Arthur, while still clashing swords with Hendrickson, displays shock again.

Seeing Meliodas' Black Mark, Arthur lets Hendrickson elbow him in the stomach. The king of Camelot asks Hendrickson about the demon powers only for the latter to retort that why should he bother to tell when Arthur's going to die. Then Arthur received a burn from Hendrickson's Hellblaze and panicked but was swiftly saved by the cloaked person, whom he thanked. He then tells his partner to stand back as he got this to which Hendrickson calls him an idiot. Arthur ends up being heavily injured by Hendrickson while the latter went off to battle Meliodas. Arthur apologized to Meliodas for not buying enough time, but the latter told Arthur to rest for now and leave the battle to him. Arthur started to blame himself as he was not strong enough, but the cloaked person told Arthur that he performed admirably and just surviving a fight against a Great Holy Knight of another kingdom is significant. The cloaked person said that Arthur's first battle was well done and should watch Meliodas battle as it would serve him in the future where he is destined to lead Britannia one day.

Gilthunder changes sides and joins Meliodas and Arthur's side, and defeats Hendrickson. After the battle, Arthur tags along with Gilthunder, Margaret, and Meliodas, and they join up with the other group with the goal of rescuing Bartra and Elizabeth. Arthur compliments Meliodas and his heroic deeds including saving Gilthunder and Margaret. The clueless group confess that they have no idea who Arthur is. Arthur informs them that he is the new king of Camelot, and he is here because he heard that Bartra was in trouble, and came to rescue Bartra. Gowther questions if the power they sensed earlier was him, at which Arthur confirmed. Meliodas then wonders why Arthur didn't use it, and Arthur admits that he has no knowledge of what his power might be and wanted to fight a Great Holy Knight so his power would awake, but unfortunately, it did not. The group are dumbfounded at Arthur, and some commented that he is an idiot for fighting a Great Holy Knight without any powers at all.

Suddenly, Arthur and the others are teleported to a forest by Vivian, but fortunately, they are soon sent back to Liones by Arthur's mysterious cloaked friend. The cloaked figure is soon revealed to be Merlin of the Seven Deadly Sins. After the situation, Bartra started to cough blood which alarmed everyone until Merlin came and offered to heal him back in Camelot along with Arthur. As Merlin was about to leave through teleport, Arthur told her to wait as he went to Meliodas and offer him the title and rank of Great Holy Knight of Camelot as he believed that they were fated to meet. Everyone was surprised and shocked at Arthur's offer, but Meliodas accepted Arthur's offer to Elizabeth's dismay as Meliodas believed that since the kingdom is saved, Elizabeth is freed, and Dawn Roar will take over the Deadly Sins job, there would be no need of him in Liones. Arthur was pleased with Meliodas acceptance, but Meliodas told him not yet as he need to be in the kingdom to restore it, and he still has the Boar Hat to run. Meliodas then asks Merlin if she will rejoin the Deadly Sins who said not right away and teleported along with the sick Bartra and the depressed Arthur. However, as a result the three didn't know of the next dire situation happening to Liones as Hendrickson caused the Demon blood of the New Generation to awaken and mutate them into hybrid Demons to rampage around the kingdom.

Albion arc
Later back in Camelot, Arthur and his kingdom's Holy Knights prepare themselves for battle against mysterious gigantic figure threatening his country, that appeared out of nowhere, just as Bartra said that the omen of the Holy War sets in the south of Britannia. As the mysterious giant figure approaches his kingdom, Arthur sets out orders to knights and Holy Knight Apprentices to focus on the evacuation of his people and readies all Holy Knights for battle before being informed of a flying giant pig hovering above Camelot much to their shock.

As the Albion reacting to Meliodas and his team's power level, Arthur and the Holy Knights could feel the tremendous "desire to kill" aura from the Albion.The Albion tries to destroy Merlin's Perfect Cube that has been set by her to protect the whole Camelot by punching it over and over but its attack doesn't do any damage. Desperate, it shoots a flame to the barrier. Arthur panics and orders the anti-air magic to neutralize the attack. With their attack, the Holy Knights succeed to neutralize the Albion's attack. Arthur congratulated them, but he was sure that they will not survive the second attack.

As what Arthur afraid of, the Albion shoots another flame. The Holy Knights desperately try to shield their king with their own bodies, but the Albion attack is reflected by Meliodas' Full Counter. Following Meliodas, Arthur ordered the Holy Knights to climb the Albion's arm. Arthur got trapped under Albion's hand, but Meliodas saves him quickly, breaking Liz's Sword in the end.

After Meliodas gets his Sacred Treasure, Lostvayne, back from Merlin, he slices Albion's left arm easily in one move which impresses Arthur. Finally, Meliodas defeats the Albion using his special technique. Arthur jumps from Albion's body and happily runs toward Meliodas, asking what moves that he made a while ago.

As the situation calmed down, Meliodas tells Arthur about Ten Commandments' backstory, the organization who work under the Demon King who send the Albion to destroy Camelot. As he and Diane grow afraid, Galand, a member of Ten Commandment landed on Camelot, making Merlin quickly moves to Arthur's side as Hawk tells her that the power level of the commandment is 26,000.

During Galand's appearance, Arthur keep worries and unfocused. He watches in horror as Galand swings his spear and destroyed a large inhabited area.Merlin acts fast as she creates Perfect Cube spell on Arthur and Elizabeth. However, Galand confronts her and pushed her to making a false agreement. Arthur once again watches an unimaginable event as Merlin's body suddenly petrified completely. Unknowingly, Galand's commandment is "Truth" and people who tell lies in front of him will turn into stone. One by one fighter has been turned down by Galand. Before he could reach Arthur and Elizabeth, Gowther, who has return to his human form, emerges.

Istar arc
After Galand left, Arthur cries besides Merlin's petrified body, blaming Merlin's death on himself. However, Merlin revealed that she transferred her soul to her Sacred Treasure, Aldan, before her body could be petrified completely, making Arthur relieved. Merlin informs that the Seven Deadly Sins combined with their allies' power still can't match the power of Ten Commandments. She also said that if Arthur and Elizabeth could activate their power during their next battle, they could be a great hope for them. Arthur who is very pessimistic with his hidden power, is surprised after Elizabeth said that she would do anything to help everyone.

To gain more power and regain Meliodas' sealed power, Arthur and the others visit the Land of Druid, Istar. Gowther asks Arthur why he doesn't follow everyone to the center ruin, but Arthur asks Gowther the same question.

During Meliodas test to regain his sealed power back, Arthur appeared in one of his flashback visions. As the chief, Jenna lead them to the training cave, Arthur was shocked as he saw Hendrickson being alive and brought heavily wounded Gilthunder, Griamore, and Howzer with him.

Arthur looks curiously as Jenna heals the trio. After they regain consciousness again, all the group start to removing their clothes and weapons before enter the training cave. Arthur asks Merlin why she doesn't come along, she replies that she can't come because she has no physical body.

Inside the training cave, Arthur who teamed with Gowther fights a golem type monster. Before Arthur could hit the monster, it splits it body but shut down by Gowther with his ability Hijack. However, the spell doesn't affect it and beheads Gowther. Arthur shouts in panicked, but is relieved as he sees Gowther is still alive although his head is separated from his body. Gowther reveals that someone must be controlling the monster.

Somehow, Arthur and Gowther managed to defeat the monster and returned to the cave entrance. Outside, Merlin notices a creature sitting on top of Arthur's head. When she asks Arthur what the strange object on his head is, Arthur and Gowther merely reply, "It's a mystery". After Arthur and the others bide their farewell to Jenna and the others, Gowther tries to pull Cath from Arthur's head but the cat doesn't budge from Arthur.

Ravens arc
During their travel to find the Lion's Sin of Pride, Escanor, Arthur sees King leaves the Boar Hat, still shows his distrust toward Meliodas.

Great Fight Festival arc
In Boar Hat, still in their journey to search for Escanor, Arthur is surprised when Gowther suddenly quoted a line from the book "The Lost Treasure". Gowther says that he would lend Arthur the book. Meanwhile, Fraudrin, one of the Ten Commandments reveals that Gowther is a former member of the Ten Commandments.

At one point, Meliodas decides to enter the Vaizel Great Fighting Festival and Arthur, still with the mysterious cat on his head, got separated with Meliodas from the main team after they enter Vaizel's maze. Inside the maze, Arthur is impressed by Meliodas' strength when he defeats four Earth Crawlers alone. Both of them agree that the taste of cooked Earth Crawler is very bad.

After they dumped the cooked Earth Crawler, Arthur recalls that he hasn't done anything to pay Merlin's kindness. Merlin found Arthur by the wayside and since then, she has mentored him until now.While they are talking, Meliodas suddenly feels Elizabeth's presence across the thick wall of the maze, making Arthur wonder. While Meliodas is thinking about how to across the wall, he and Arthur find cooked Earth Crawler's meat. They soon eat it over and over after they find that the taste of the cooked meat is very delicious, unlike theirs. It revealed that the cook of the meat is the Fox's Sin of Greed, Ban. Arthur watches Meliodas and Ban's reunion in awe and could feel the changing atmosphere after Ban's appearance.

Arthur, Meliodas, and Ban later teamed up to find Elizabeth and the others. Meliodas and Ban try to find a way to destroy the wall, but Arthur insists that they can't break the wall due to its fast regeneration.However, Meliodas and Ban's power could penetrate the wall and order Arthur to follow them across the wall before it could regenerate. Arthur envies Meliodas as Elizabeth and Ban trust him so it helps Meliodas become the most powerful warrior that he is known to be.Meliodas tells Arthur that the most important part is how you feel towards people, not what the others thinking about him. Arthur then become more determined to save Merlin.

Arthur meets with all the other participants at the end of the labyrinth, where they are received by Drole and Gloxinia. There, Drole creates huge hands of land where will be the stage for the fight festival while Gloxinia kills all those who remained in the labyrinth, which surprises Arthur. When Drole divides everyone into teams of two, Arthur is paired with Nanashi, showing himself pleased.

After Escanor left Drole and Gloxinia disabled during their fight, Meliodas comes out to face them. Arthur is surprised to hear Meliodas' true plan to face them when they let their guard down during the festival. Then, Arthur is taken hostage by Drole along with all the other festival participants except Meliodas, being trapped inside his Giant Embrace. All are then teleported by Gilfrost to Liones where they observe the battle of Meliodas against Drole and Gloxinia by Gilfrost's crystal ball. When the other seven Commandments arrive at the battle, Arthur mentions that there is one, Galand, who is absent, revealing to him Jericho that this one was defeated by Escanor. Upon witnessing the death of Meliodas at the hands of Estarossa, Arthur breaks into tears.

Defensive Battle for Liones arc
During the invasion of the Demon Clan in Britannia, Arthur along with Nanashi and some soldiers decide to release Camelot that had been taken by them. They all face a horde of Gray Demons, when he tells them to choose whether to die or surrender, Arthur claims that they will defend their home until the end. In the end, Arthur and his group manage to defeat the demons. The soldiers praise their king as the light that guides them, although Arthur claims that they would never have achieved it if not for Nanashi. When Nanashi says that while Cath is with him he will not see death, Arthur asks him what he means. When the demon reinforcements attack them, Arthur orders retreat, claiming that he must still become much stronger.

Prelude to the New Holy War arc
Arthur appears to have survived his battle with the demons but unable to prevent Zeldris from having control of Camelot. In the middle of the open field, the king finds Orlondi calling out Merlin's name and drawing Arthur's attention. After escaping the presence of an Orange Demon, Arthur takes Orlondi to an underground hiding place where the survivors of Camelot are protected. There, Arthur is well-received by everyone and presents Orlondi as one of Merlin's servants. Orlondi tells Arthur that all humans controlled outside are being used as sacrifices to break the seal of the Goddess Clan and release the rest of the Demon Clan, Arthur tells him that since they are all having terrible moments, it is necessary to stay positive so as not to lose hope to what the citizens tell him that he is the only reason why they do not lose hope and that they are sure that he will manage to recover Camelot. When Nanashi informs him of his recognition that 55 demons were already released from the seal, Arthur reveals that he has already eliminated half of them, revealing the growth he has had in recent months. There, Nanashi says that it is time to carry out his plan, revealing that Arthur plans to infiltrate into the castle and recover Camelot himself. Orlondi tells him that it is crazy and that they will only kill him, but Arthur says he will get it if he manages to recover the holy sword, Excalibur.

When Arthur and Cath leave to the castle to recover the Excalibur, Arthur does not understand how they can not approach asking if they are caught in some kind of illusion. When a Gray Demon attacks them, Cath manages to get rid of Peronia, who was using her magic to get them away from the castle.

Once inside, Arthur is surprised by Zeldris and Cusack, being completely intimidated by the magic power of both demons. When they ask him his identity, Arthur reveals to be the king of Camelot, allowing Zeldris to deduce that he is looking for Excalibur. When Cath manages to distract the demons to give Arthur the possibility of escape, he promises to help him again. On the way he looks at Chandler, wondering how many monsters like him there are there. When he finally reaches the room where Excalibur is, Arthur is attacked on the back by Zeldris and Cusack, who show Cath completely wounded and defeated. There, Meliodas appears affirming that Arthur is a condo of his and tells him that this is no longer a place for humans like him and that he should get away. Arthur asks without understanding how Meliodas is with the demons, to which Meliodas responds that he cut his ties with the Seven Deadly Sins and is no longer the person he once knew. Arthur is outraged to discover that the man he admired betrayed his companions and the woman he loves, vowing never to forgive him. At that moment Arthur manages to take Excalibur and declares that he alone will defeated Meliodas and the other demons.

While Meliodas and Zeldris argue about the strange aura that the sword emits, Chandler appears and attacks Arthur with Exterminate Ray. However, the attack has no effect on Arthur, who cuts Chandler's head off. Then, he cuts off Cusack's arm to retrieve Cath and apologize for what he forced him to suffer. When Cusack asks him how he knows that sword technique, Arthur cuts his body in three parts and then attacks Meliodas and Zeldris, destroying part of the castle in the process. Zeldris attacks Arthur from behind, but the king defended with Mumyo no Mai. Zeldris wonders how he knows that old technique to which Arthur tells him not to underestimate humans, proceeding to attack him with Deathpecker. Both Meliodas and Zeldris recognize these techniques as those belonging to the ancient masters of the sword and understand that they are dealing with the power of Excalibur. Arthur manages to evade the attacks of Meliodas and Zeldris and deal them blunt blows with Excalibur. However, these fail to make a dent in the two demons.

Meliodas and Zeldris are not injured by Arthur's attacks. When Arthur asks how they are still alive, Chandler and Cusack appear to have recovered from the injuries that Arthur caused them, revealing that in reality they only wanted to test the power of the sacred sword. When Cath tells Arthur that his magic power is still asleep, Arthur says that he will not lose as long as he has Excalibur, but there he falls completely weakened. Cusack tells him that he made two serious mistakes by abusing the power of the sword without having the power to resist the force of the heroes of the past and recklessly face high-level demons like them. Looking into his eyes, Cusack put him under his Resonant. Before that Cusack could kill Arthur, Merlin appears and traps Cusack in her Icicle Castle and then proceeds to teleport along with Arthur to the Boar Hat. However, Cusack uses the connection created between him and Arthur by Resonant to force Arthur to pierce his own heart with Excalibur, to the horror of Merlin and the Sins. Merlin desperately asks Elizabeth to heal him, but she tells him that she can not do it unless Excalibur is removed. In his last moments, Arthur apologies to Merlin for not reaching her expectations.