|“||Look at the half man with his half sword, solving riddles from a tree!||„|
|~ King Arthur to Merlin|
|“||I was once prophesied to repair a broken kingdom. My mistake was thinking that kingdom was Camelot. But now I think I understand. The kingdom I have to repair is here. The Underworld.||„|
|~ King Arthur to Hook|
As young children, a romance blossoms between Arthur and Guinevere. While walking in the village of Camelot, Arthur relates his dreams of Camelot becoming a great kingdom with him as their king. He promises Guinevere that they're not only dreams and he tells her a secret about a powerful sorcerer who is trapped inside a tree, recounting the night the sorcerer spoke to him, prophesying that he would one day pull a sword from a stone, and become King Arthur of Camelot. He wishes to make Guinevere his queen, promising to fill the kingdom with her favorite flowers, middlemists, on her birthdays. Arthur begins leading her to a meadow of middlemists, but upon seeing a sword stuck in a stone, he halts, fearfully realizing it belongs to Kay, who promptly shows up to disparage him and his prospects as king, much to Guinevere's dismay. He sneers at Arthur's dreams, stating that Camelot is the Broken Kingdom because they have no king and never will, adding that no one would ever kneel to the orphaned boy who cleans the stables. Arthur wonders if Kay is right, but Guinevere assures him that Kay isn't and Arthur will find the sword as long as he follows his heart.
Years later, Arthur travels with Lancelot and Percival to find the Excalibur in the stone after Merlin prophesies that Arthur is fated to become the realm's ruler by pulling out the sword. When Sir Kay beats them there, Arthur cautions him to not give into darkness since the sword doesn't belong to him. Having little belief in the prophecy, Sir Kay tries his hand at taking the sword out, only to be turned into ash by the sword's power. As Lancelot and Percival look on, Arthur succeeds in pulling out the sword, but strangely, the blade's tip is missing. Arthur momentarily panics over this, but he then decides to keep it a secret from the kingdom's people, and that all they need to know is he is now their king.
After returning to Camelot, Arthur proves himself king to the entire village by partially unsheathing the sword. He is then greeted by Guinevere's loving embrace, but she soon realizes something is wrong. In clandestine, he tells her that the sword is missing its blade tip and that he needs to make it whole again.
Arthur bestows the Round Table's Siege Perilous seat, which is only fit for a knight with the purest heart, to Lancelot, who is his most trusted friend.
At some point, Arthur learns the missing part of the Excalibur is the Dark One's dagger, and he seeks to find it so Excalibur can be made whole again.
During his reign, Arthur becomes so consumed in his quest that he begins neglecting Guinevere, who attempts to persuade him into dancing with her on her birthday. He finally accepts and asks her to wait for him, but then continues to research. In the meantime, Guinevere realizes that it wasn't Arthur who prepared her birthday celebration, but Lancelot. Suddenly, Arthur runs up to them in delight, telling Guinevere that he discovered the location of the dagger is a day's ride from the village. Lancelot prepares to go, but Arthur insists he stay and protect the queen, while he himself goes on the journey. When Arthur leaves, Guinevere uses a magic gauntlet that points to Arthur's greatest weakness, which, at that moment, is the dagger. She realizes that Arthur has the wrong location and leaves to find the dagger herself, with Lancelot accompanying her. Having returned empty-handed, Arthur sees Guinevere have a romantic farewell with Lancelot and later confronts her. She tells him that they found the dagger, to which he begins searching her satchel for it. Upon finding nothing, Arthur demands to know where it is, so Guinevere shows him a vial of enchanted sand that can fix anything. He becomes angry at her idea of using an illusion to make Excalibur whole again, but Guinevere argues she just wanted his love again, but now, she realizes she desires something else. Arthur assures her that she will be his, only if she tells him the location of the vault. Instead, she asks him to make a choice, or he will be left with a broken marriage and kingdom. He asks her what would happen if he cannot surrender the quest, to which she says that she'll follow her heart. Believing she will go to Lancelot, a paranoid Arthur tosses some sand on her. Blinded by magic, she decides to support him, to his delight. Later, he disperses more sand from Merlin's tower, which magically transforms Camelot into a castle. Following Lancelot's departure, the Siege Perilous seat becomes vacant, with Arthur unable to find another person to fill it again.
Somewhere in the Enchanted Forest, King Arthur and his knights approach Emma and some of her allies. He informs them that a prophecy has foretold they will help reunite Camelot with Merlin, who is currently missing. King Arthur then leads them to his castle in Camelot.
Arriving at the castle, King Arthur introduces his guests to his Queen, Guinevere, and then announces there will be a ball held in their honor. He later shows them a tree in the courtyard which Merlin is trapped in and learns from David that they are desperate to find Merlin in order to defeat the Dark One. When Arthur asks who is the prophesied savior, Emma prepares to speak up, but Regina claims the title in her place, not wanting Emma's cover to be blown. During the ball, Arthur and Guinevere are present during the festivities. Things take a tragic turn when Percival attacks Regina, but Robin intervenes, getting injured in the process. Before Percival can give Robin a final fatal blow, David saves Robin by killing Percival. In the aftermath, Regina outs herself as the former Evil Queen that once massacred Percival's village, which is why he wanted her dead. Arthur believes in second chances though, and takes Regina's feat in healing Robin's wound as a sign that she truly is the savior, not knowing it was actually Emma who used her Dark One powers to heal Robin. Later that night, Arthur is sitting at the Round Table with Percival's shield when Guinevere comes to talk to him about their guests. She fears trouble on the horizon because of them since they know what will happen because of Merlin's prophecy, but they don't know how. Arthur insists they will have to see it through since the newcomers want to destroy the Dark One, and while it'll be difficult to do, it's the only way to obtain the Dark One's dagger and finally unite Excalibur with it. He reasons that if Excalibur is not made whole, they'll lose the kingdom they worked so hard to build. As a show of acceptance of what they must do, Guinevere places her hand over Excalibur, while Arthur puts his hand over hers.
As Regina researches for magical remedies to free Merlin, Arthur comes to check up on her. Getting inspiration from Mary Margaret, Regina realizes they need a toadstool, the crimson crown, which can communicate with someone through any magical barrier, namely Merlin. Arthur believes it is in the Brocéliande, the Forest of Eternal Night, but the item may only be a myth. David insists on going, so Arthur agrees to accompany him, after they get weapons at the Round Table room. There, Arthur tells him about the seats of the Round Table, which are of equal status among himself and the other knights except for the Siege Perilous, a seat he once bestowed to the knight with the purest heart,Lancelot, until he was betrayed by him. When David reveals Lancelot died, Arthur is saddened by the news, lamenting that Lancelot was a good knight despite his fall into temptation. Arthur's squire, Grif, brings them a relic chest, and from it, Arthur takes a torch called the unquenchable flame to help guide him and David through the forest. On the way there, the men find common ground, with both of them having been born commoners and risen above their ranks. Within the forest, they spot the toadstool on mossy land, but someone must cross a water logged bridge to get to it. As Arthur watches nervously, David makes the journey and pockets the toadstool, but on the way back, he is attacked by reanimated dead knights. Upon seeing one force David underwater, Arthur pulls him to safety. Without the latter's notice, Arthur steals the toadstool, which David later believes was lost during the underwater struggle. With the quest being a failure, Arthur and David discuss the irony of their claims to fame; Arthur's being the prophesied king, and David's being his princess' rescuer, although both desire to be known for more than just that. They agree that it's through loss that there is strength to be brave and heroic. That night, Arthur makes David a knight of the Round Table and gifts him the Siege Perilous seat. Later, Arthur reveals to Guinevere that he stole the toadstool, in order to protect the kingdom.
Now that David is a knight of the Round Table, Arthur reveals the truth about Excalibur's missing half to him. Not having much faith in whether Merlin is their only hope, he asks for David's assistance with finding the Dark One's dagger to make it whole again, which will give him the power to purge the Darkness for good. David leaves to think it over, and upon returning, he confesses that Emma is the Dark One, which is why he needs the Darkness banished. To the latter's relief, Arthur is sympathetic to his situation, agreeing to help get rid of the Darkness in Emma. David reveals Lancelot is alive, and though Arthur intended this to remain a secret between them for now, Guinevere overhears them and bursts in, demanding to know the former knight's whereabouts. Arthur fears the dagger isn't safe now that Lancelot is in Camelot, to which David opens a box to show them the dagger, only to realize it's empty and Mary Margaret must have taken it. While David searches for her, Arthur follows Mary Margaret and Lancelot into the Vault of the Dark One, where they prepare to hide the dagger. Arthur forces Mary Margaret to give it to him, and he then attempts to summon the Dark One, but it fails. Mary Margaret admits the dagger is fake, before David takes him unawares from behind, revealing he and his wife were conspiring against him. Handcuffed, Arthur is led into the diner by the trio, who make plans to unite Excalibur and the dagger, as well as install Guinevere as the new ruler of Camelot. Instead, Guinevere ambushes them with soldiers, freeing Arthur, and orders for Lancelot's imprisonment after taking Excalibur back. Left with David and Mary Margaret, Arthur allows Guinevere to do the honor of blowing enchanted sand onto the couple, in order to gain their compliance with getting the real dagger.
With some of his soldiers, Arthur confronts Regina and Emma at the Merlin tree, where the women are in the midst of concocting a potion to free the sorcerer. He demands the dagger, but rather than obey, Regina slips Emma the last ingredient to combine for the potion. Arthur and his men attack, only to be blocked by Regina's incoming fireballs. After the potion is complete, it actives a stream of light and dark magic that Emma harnesses, using it to revert Merlin to human form. The sorcerer confronts Arthur about the disappointment he turned out to be, while the king fumes about Merlin giving him false prophecies that ruined his life. Arthur moves to unsheathe Excalibur, but Merlin coolly cautions him against it, warning that they both know the sword, in its uncompleted form, is useless against him. Refusing to accept defeat, Arthur threatens that things are not over yet, before he and his men retreat. In retaliation against the heroes because they freed not only Merlin, but also the imprisoned Lancelot and Merida, Arthur frantically makes a cauldron potion to destroy them for conspiring against him. When his guards arrive, he orders them to get reinforcements to arm all sides of the castle. Taking a guard's helms, Arthur pours some of the potion onto it, which melts and eradicates it to nothingness. He then orders his soldiers to take the cauldron and throw it on any intruder they see. Later, in the Round Table room, Arthur prepares Excalibur and a spell book, just when the heroes burst in to apprehend him. Regina freezes him with magic, and when she boasts that Arthur does not know how to use magic and therefore cannot hurt them, Arthur gives her a knowing smile, just as his accomplice Zelena hauls in a captive Mary Margaret to subdue the group. Zelena unfreezes Arthur and proceeds to cast a spell to tether Merlin to Excalibur, giving Arthur the power to summon Merlin to him. Arthur confronts the sorcerer about making him into the man he is today because of the false prophecy and broken sword. Merlin offers to help him reunite the sword and dagger and restore all that was lost, but Arthur believes there is no going back, and he doesn't want Merlin to have all the glory. To this, Merlin disapproves, upset that Arthur only cares about his own reputation. Shutting down the conversation, Arthur orders the sorcerer to disarm the heroes and send them away, which he does.
For an unexplained reason, Emma erases everyone's memories of the six weeks when she and her allies were in Camelot, with everyone last's memory being entering King Arthur's castle. She then sends them as well as some residents of Camelot to Storybrooke. Shortly after arriving to there, King Arthur and two of his knights ride through town and spot Leroy and Happy. The knights quickly disarm the men, to which Arthur takes off his helmet and demands they explain why he was brought to this land. At the mayor's office, Arthur learns from Regina that the memory wipe and realm transportation is part of a curse. Recalling that they spoke of the Dark One's identity during the journey to Camelot, David admits he was dishonest about it, to which Mary Margaret reveals the Dark One is their daughter Emma and that she cast the curse. Upon Robin Hood notifying them about other Camelot residents scattered in the woods, Arthur goes with David to search for them. After everyone is found, some of the townspeople help distribute supplies to the Camelot visitors. Arthur sets up his tent in the forest, where Guinevere finds him and notices Excalibur is missing, but David assures the couple that they will find it. When a fury kidnaps Robin because of an unpaid price of magic, Regina is hurt while trying to rescue him, leaving Arthur, David, Mary Margaret and Leroy to chase after the fury. By nighttime, they intervene when the fury summons a keeper of the underworld to take Robin's life, only for the fury to magically stun them. Regina forces the fury to take her life instead, but Mary Margaret refuses to abandon her, linking her hands with her. As the fury begins absorbing them, David, Leroy and Arthur join the women, causing the fury's power to explode on itself, which pays off the price of magic.
Growing distrustful of the Storybrooke folk, particularly after their admission that Emma is the Dark One, Arthur makes secret plans to make the town the new Camelot for his people, while he continues to gain David's trust. As part of the setup, Arthur tells his squire, Grif, to later steal a relic chest. Arthur lies to David about someone taking a magic bean that he and his people need for returning home. They examine the chest that had the bean, in which David asks Grif for any theories about who did it. Without David's notice, Arthur shoots Grif a knowing look, to which the squire talks about the Dark One possibly being culpable. David admits Emma recently stole a dwarf pick ax, though Arthur recalls him saying the Dark One doesn't need weapons, and he then points out the chest has scratch marks on it. At the pawnshop, they question Belle about anyone pawning a magic bean, but she knows of no such person. To improvise, David takes a chalice that has no magic, but he announces to the Camelot group that they must drink from it so the the magic bean thief can be found. Soon after, Grif flees on horseback, leading Arthur and David to follow him in a truck. At one point, Arthur must assume control of the wheel, as David maneuvers to the back of the truck to grab a wooden beam. On David's insistence, Arthur drives around in a circle, in order to corner Grif, who David knocks off the horse with the beam. Afterwards, Grif "confesses" to stealing the chest, under the pretense of being fed up with how Arthur was treating him, but he doesn't recall there ever being a bean. David privately asks Arthur if he believes Grif is lying, but the latter denies it. David promises to help him find another way home, and then prepares to lock up Grif in a cell, when he and Arthur discover a toadstool that came over from Camelot during the curse. Later, Arthur visits Grif in his cell and convinces him to ingest a fatal viper poison, for Camelot's sake, so the Storybrooke townspeople will never learn the truth.
When Grif's disappearance is made known to the others, Arthur calmly deducts that his squire must have been lying about not having the magic bean and used it to return to Camelot alone. Guinevere grows concerned with how this development will affect her people's spirits, so the Storybrooke natives decide to throw a town party as a much needed distraction. As they all leave the sheriff's station together, Belle runs up, reporting that Mr. Gold is missing. Later that night, during a town carnival, Hook and his allies reveal to Arthur, Guinevere, David and Mary Margaret that they searched Emma's house and found Excalibur hidden in her basement. After some questioning by Hook, Arthur confesses to knowing the Dark One's dagger is Excalibur's missing blade, and that if the sword is made whole again by uniting them, the combined weapon can extinguish the darkness, but in Emma's hands, she may use it to snuff out the light. Once the Storybrooke group figure out they can use the crimson crown to communicate with Merlin, they call in Arthur to enact the spell, as only someone who was chosen by the sorcerer can harness the toadstool. Arthur pretends to be helpful and forthcoming, but when it comes time to throw the crimson crown into the prepared cauldron brew, he hesitates, suggesting Merlin might only talk to him if he's alone, as that is how they spoke in the past. After everyone leaves the room, Arthur tosses the toadstool into the burning fire under the cauldron. Outside the vault, he tells them that the spell fizzled out and didn't work. While Arthur believes the toadstool is burned to nothingness, the group later find the charred but still whole crimson crown in the fire's ashes, proving that Arthur is conspiring against them.
As Arthur enjoys a candlelit evening with his wife, David enters to confront him about his attempt to destroy the crimson crown. The spell, however, was successful, giving David reason to question him about Nimue, someone Merlin mentioned who can defeat the Dark One. No one says anything in response, to which Guinevere stands up and signals a look to her husband, and as David continues to wait for an answer, Arthur flips the table and cuts an opening in the tent with his sword to flee on foot. Hook tails him into the woods, where Arthur fakes tripping over a tree trunk, in order to shove Hook to the ground and hold him at sword-point. Before he can finish off the pirate, Emma blocks him with Excalibur, which has since been reforged with the dagger, before flinging him hard against a tree, knocking him out. After Arthur's imprisonment in the sheriff's station, Hook tries to force the truth out of him about what happened in Camelot. When it's clear Arthur doesn't have the answers, David gets Hook to back off, by referring to Arthur as a king without a kingdom who has little importance to them now.
Following the heroes' adventures in the Underworld, Arthur escapes captivity when Merida mistakenly puts Sleepy in charge of watching him. He stumbles across Hades, and insists that he was imprisoned falsely. Hades notes that he, too, has been imprisoned falsely before, and like Arthur, also believes he deserves to rule a kingdom, in this case, Storybrooke. He then snaps Arthur's neck, leaving the ex-king's corpse on the bridge, which is later discovered by Merida, who admits that though she wanted to kill him, she now feels sorry for him.
After his death, Arthur lands in the Underworld because of his unfinished business. Having no idea he's dead, he stumbles into Underbrooke's diner, where he learns the truth from Hook. When Arthur admits someone named Hades killed him, Hook requests his help to find Hades' weakness. Arthur consents only after Hook introduces him to the concept of Mount Olympus and the "Worse Place", suggesting that if Arthur does a good deed like helping him, he may move on to Mount Olympus. The pair head to Hades' lair, where Hook explains that they need to look for pages from the Underworld's storybook that contains information about Hades' weakness. Arthur soon realizes that Hook's desperation is due to a woman, and after hearing Hook's full story, he feels sorry for the man. Hook asks him, as a king, where he would hide his most precious treasures, and Arthur states he'd hide it in the one place that no one will touch; the throne. His theory is correct, and the pair take the pages back to Underbrooke. The men then drop by the diner to interrogate Cruella about the book's location. Cruella, clearly taken by Arthur's good looks, briefly flirts with him. After she reveals the book is in Acheron, Hook and Arthur take a boat ride across the river. During this, Arthur reaches for one of the souls in the river, only for Hook to warn him that touching the water will turn him into a lost soul. Once the boat docks, they see the book in the arms of a gargoyle statue. Hook goes to get it, while Arthur is grabbed by a soul emerging from the river. Arthur urges him to go on instead of helping him, but Hook, unable to abandon the man, burns the soul with a torch. As Hook heads towards the book, another soul snatches it. Arthur kills the soul with fire, but as the soul dissipates, the book nearly falls into the river, but Hook grabs it in time. In the hopes that Emma will receive the message, Hook places the pages about Hades into the book. Awhile later, Hook senses that Hades has been destroyed, and a bright light appears within the nearby doorway leading to Mount Olympus. With Hades' defeat being his unfinished business, Hook suggests that it may be Arthur's as well. Instead of joining Hook, Arthur decides to stay in the Underworld and fix it, as he was once prophesied to repair a broken kingdom. While he believed it to be Camelot at the time, he now realizes that it is the Underworld. As Hook leaves for Mount Olympus, Arthur stays behind to repair the Underworld.
- Arthur is the main antagonist of the flashbacks portion of the first half of Season 5, along with Zelena. In the present time, the role goes Emma Swan until Nimue and her ally Captain Hook arise as the true villains of the whole season.
- This version of King Arthur is similar to King Stefan from Maleficent; they are villainous kings who started out good, but were driven to evil and madness by the people closest to them (Arthur: Merlin, Stefan: Maleficent) and became obsessed with destroying them, which ultimately led to their defeat.