Gaius is the court physician of Camelot and has been for the last twenty years, since Prince Arthur Pendragon was born.


Life before the series

Prior to becoming court physician Gaius practiced magic with Nimueh. He rose to prominance when the queen died in childbirth and Nimueh failed to save her. She was subsequently banished from the court, becoming an enemy of both King Uther and Gaius. At the same time Uther banished the use of magic in the kingdom and Gaius, unlike Nimueh and many others, stopped practising magic. However, during the Purge, Gaius helped three people who would later return to Camelot as friend or foe; Balinor, Morgause and Alice. He hid Balinor, a Dragonlord, with his friend Hunith, smuggled a baby Morgause out of the citadel and gave her to the High Priestesses of the Old Religion and crossed Alice's name off a list of sorcerers to be arrested and executed.

Merlin's mentor

Gaius was the guardian of Merlin, who was sent to him by his close friend, Hunith. Hunith feared the repercussions Merlin would face should his powers be discovered by Uther or his men. Upon his arrival, Merlin saved Gaius from falling to his death from a balcony in his room using the powers. Gaius quickly took a liking to the boy and promised to keep his secret about Merlin using magic. (The Dragon's Call)

Gaius acted as a parent and a teacher to Merlin. He frequently tried to encourage him in his abilities while, at the same time, advising him to look at the bigger picture such as with the plague in Camelot where Gaius tried to make Merlin see that curing one person can have consequences; subsequently Merlin cured Gwen's father, resulting in her being accused of witchcraft. Merlin and Gaius managed to find the source of the disease; an Afanc in Camelot's water supply and after the Afanc was destroyed and Gwen was freed. Gaius showed Uther an eggshell Merlin had found underground. The shell bore the mark of Nimueh. (The Mark of Nimueh)

Uther trusted Gaius's advice frequently when concerning something to do with magic, (The Mark of Nimueh, The Poisoned Chalice et al) although at times they failed to see eye to eye. (Lancelot) When Edwin Muirden manipulated Uther into believing Gaius was no longer capable of his job Gaius was removed from his post as court physician. Furthermore Edwin threatened to tell Uther about Merlin practising magic if Gaius told Uther about his own use of magic. It was only after Edwin's attempt to kill Uther, and Merlin stopping him from attempting to kill Gaius, that he was once again return to his post.

When Arthur was seriously injured by the Questing Beast, Gaius did everything he could to save the prince and managed to keep him alive long enough for Merlin to go to the Isle of the Blessed to find a cure. Arthur recovered, due to Merlin making a deal, but then Merlin's mother grew seriously ill. Merlin planned to sacrifice himself to save her but Gaius went instead. On the Isle of the Blessed he met Nimueh, whom he had known before the Great Purge. Gaius pursuaded Nimueh to kill him so that both Merlin and his mother could live. It seemed that Gaius actually did die but Merlin arrived and, enraged by the death of his friend and mentor, slew Nimueh. In killing Nimueh, Merlin restored balance to the world, mastering the power of life and death and reviving Gaius.

Gaius was later arrested for sorcery when Aredian, a witchfinder, accused Merlin of using magic and he took the blame. Gaius was locked in the dungeon and interrogated by Aredian until he confessed in order to prevent Aredian from killing Merlin and Morgana along with him. Aredian betrayed him and intended to have Merlin and Morgana executed as well. Fortunately Merlin was able to uncover Aredian's treachery and Gaius was freed, giving Uther some very harsh words on his views of magic afterwards.

Gaius was frequently seen advising Merlin or assisting him wherever he could. It was Gaius who told Merlin about his father Balinor. He was seen saving as many lives as he could during the Great Dragons assault on Camelot and later comforted Merlin about Balinor's death telling Merlin "you've still got me".

A rift arose between Gaius and Merlin when Gaius' old lover, Alice, returned to Camelot. Merlin saw Alice with a Manticore and told Gaius who refused to believe Merlin and thought that Merlin does not want for him to be happy. Merlin was forced to tell Arthur about Alice which Gaius was angry about at first, however, later on Gaius admits that Merlin was doing what he thought was best.

Possessed by a Goblin

Near the start of series 3, Gaius was possessed by a Goblin. The goblin Gaius had a craving for gold, and was very manipulative, spreading rumours about fake illnesses so he could sell 'cures' to them. A few of these had side effects- namely, the cures given to Gwen (for a fake illness), Morgana (for her nightmares, as the goblin had stolen her gold healing bracelet) and Uther (for a curse placed by the Goblin, causing him to go bald) made them fart continuously. When Merlin found out about the Goblin, he revealed his magic. The Goblin then reavealed his magic to the court, forging evidence with a magic book from a hidden section of the library. Despite Merlin's original claims of Gaius' possession being ignored, Arthur grew suspicious of Gaius' behaviour. He tricked the Goblin into saying he would be glad to see Merlin hang, and silently threatened to either kill or turn him in. In retaliation, Gaius partially turned Arthur into a donkey, giving him donkey ears, donkey hooves, and a donkey voice. Merlin and Gwen later poisoned him to get the Goblin out of his body but managed to give him an antidote before he died. Gaius then told Uther that he was possessed and that Merlin was innocent. However this was only half true as Merlin was the one who released the Goblin in the first place.

Gaius' lover

Later Gaius' lover, Alice, returned to Camelot under the influence of a Manticore. Gaius was delighted to see her and they worked together just as they had before the Great Purge. Gaius revealed to Merlin that he was in love with Alice and would have married her if not for the Great Purge. When Merlin discovered Alice was in league with a Manticore, Gaius refused to believe him. Alice poisoned Uther, forcing Gaius to realise that she had betrayed him, albeit unintentionally; the Manticore had been too strong for Alice to control. Despite this Gaius remained in love with Alice. He and Merlin managed to destroy the Manticore when Gaius used magic to blow up the box that allowed the Manticore to come from it's own world into theirs.

Gaius tried to pursuade Uther not to have Alice executed, protesting that she had not been able to control herself because of the Manticore. Uther sentenced Alice to death and Gaius visited her in the dungeon and told her that he loved her. Gaius helped Alice escape from Camelot just as he had twenty years earlier. Merlin noted that he could have gone with her but Gaius replied by saying that if he left there would be nobody to look after the young warlock.

Morgana's reign

Gaius was the only known person in Camelot, apart from Elyan, who was able to escape Morgause's immortal warriors unscathed. He was hiding in a cupboard when Merlin and Arthur returned from their failed mission to retrieve the Cup of Life. Merlin and Arthur's friends, Elyan and Gwaine took Gaius into the safety of the forest while Merlin and Arthur went to find Uther, Guinevere and any other survivors of the assault.

Gaius hid in the woods with Arthur, Merlin, Elyan and Gwaine. Guinevere and Sir Leon met them, having escaped from Camelot and they were soon joined by Lancelot and Percival. Gaius was present when Arthur uncovered the Round Table and knighted Gwaine, Elyan, Percival and Lancelot. Arthur requested that he and Gwen stay behind while they attempted to infiltrate Camelot. Gaius disobeyed the prince and arrived in Camelot in time to stop Morgause from killing Merlin, blasting her with a powerful spell and giving Merlin a chance to smash her against a pillar, wounding and perhaps even killing her. Then Merlin used Excalibur to empty the Cup of Life and deprive the sisters of their immortal army. (The Coming of Arthur)


Gaius was sensible and believed in thinking rationally about things rather than rushing to decisions. He was loyal to Uther despite the methods the king used to deal with sorcerers and the use of magic. The only person who Gaius valued more was Merlin, whom he came to love like a son. (A Remedy to Cure All Ills) Gaius also seemed to have known the Great Dragon for at least 20 years (A Remedy to Cure All Ills) and trusted his advice, but when Merlin told him that the Great Dragon cared only for himself, he did not protest suggesting he too had reason to believe that beforehand. But he also knows that there are times when the Dragons' assistance is needed.

Gaius also possessed a dry sense of humour and was one of the few people in Camelot who was brave enough to stand up to Uther Pendragon (The Witchfinder). He frequently scolded Merlin about using magic but knew when using magic was necessary. Gaius was willing to give his life for Merlin which was shown in two episodes.

Although Gaius was a good person, he had a habit of keeping secrets, particularly from Uther Pendragon. However Gaius only kept secrets because he, unlike Uther, knew that magic could be used for good and he was still loyal to the king and never considered turning against him even after Uther nearly had him executed. Gaius would also risk the wrath of the king if he felt it was necessary and helped Balinor and Alice escape from Camelot, risking execution by doing so. He was also cunning and he was the only known person in Camelot, apart from Elyan, who escaped Morgause's immortal army unscathed.

Many years before the series began, Gaius helped Balinor escape from Camelot despite the fact that if he'd been discovered helping the Dragonlord he would have been executed. Because he helped Balinor, the Dragonlord felt he owed Gaius a debt that he had to repay and referred to him as a good man. Gaius was also extremely dedicated to his job as Court Physician and would never give up on a patient no matter how serious the illness or injury.



Gaius was very close to Merlin, thinking of him as the son he never had. He was willing to give his life for Merlin which was proven on at least two occasions. (Le Morte d'Arthur, The Witchfinder) Gaius was very proud of Merlin but sometimes scolded him about using magic, unless it was for good reason. He often provided Merlin with advise and comfort and was seen hugging him on several occasions. In return Merlin loved Gaius like a father. They also joked with each other at times.

When Gaius was possessed by a Goblin Merlin poisoned him to get the Goblin out of his body but he and Gwen managed to give him an antidote before he died. Gaius felt no resentment towards Merlin for poisoning him as he understood that it was the only way to get the Goblin out of his body and their relationship remained as close as ever. While waiting for Gaius to recover from the poison, Merlin called him a "stubborn old goat".

Later when Gaius' lover Alice returned to Camelot he and Merlin had a falling out because Gaius refused to believe that Alice was being controlled by a Manticore. When Merlin brought guards to arrest Alice and told Gaius that it was either him or her, Gaius responded by telling him that it was not his choice to make. However he still loved Merlin and after helping Alice escape Camelot he stayed behind to look after him. Their relationship quickly returned to normal when Alice escaped.

When Merlin was attacked by Morgause, Gaius attacked the sorceress himself in order to protect him and by working together he and Merlin managed to defeat Morgause.


Gaius is a good servant and loyal friend to Uther despite Uther's hatred of magic. He has saved Uther's life many times through his skills as a physician. However after being wrongly accused of magic a furious Uther ordered him to be put to death but Gaius was later proven innocent. When Uther tried to apologise for Gaius' suffering at the hands of the Witchfinder, Aredian, Gaius told him that it was not Aredian who was responsible for his suffering, but Uther himself. He also told him that he wasn't the only one who was wrongly accused of using magic and that not all had been as lucky as him. Gaius was one of the few people who could speak to Uther however he wanted and though he was usually polite to the king he would sometimes stand up to him and point out his mistakes. After discovering Gaius was innocent, Uther's trust in him strengthened so much that he even gave him permission to use magic to heal Morgana after she fell down a flight of stairs.

Though he was very loyal to the king, Gaius often had to keep secrets from Uther, most notably the fact that he was hiding a sorcerer right under the kings nose. Despite his habit of keeping secrets Uther trusted Gaius and valued his advice and friendship.


Gaius has treated Morgana for many years and she trusted him greatly, sometimes going to him after having a nightmare. Gaius realised that Morgana's dreams were visions of the future, though he tried to pursuade himself otherwise. He frequently gave Morgana remedies to try and get rid of her nightmares but they didn't have much effect. But despite his caring for Morgana, Gaius agreed with Merlin's choice to poison her when she was responsible for a spell that was affecting all of Camelot, saying that he feared Morgana chose to use her gift for evil. When it was revealed that Morgana is Uther's daughter he feared that Morgana found out. It is unknown whether if Morgana knew that Gaius helped Merlin to defeat and apparently kill Morgause and if she did it is unknown how she felt towards him.


Gaius and Arthur shared a mutual respect for each other and Arthur knew Gaius well enough to realise that he was being possessed by a goblin. At first, Arthur didn't believe that Gaius was, or ever had been, a sorcerer.


Gaius was friends with Guinevere who went to him when she discovered her father was dying. Gwen also gave him a kiss on the cheek when he was about to leave Camelot (A Remedy to Cure All Ills).Gaius eventually discovered Guinevere's secret relationship with Arthur Pendragon; he approved and gave Gwen new hope for the relationship(The Last Dragonlord). Gwen helped save Gaius' life on two occassions, first when he was about to be burned at the stake by Aredian and later when he was dying from poison after being possessed by a goblin. She also went to Gaius and told him that she had discovered Morgana using magic.


Gaius seems to have a very good relationship with Hunith , Merlin's mother. She entrusted him the training and well being of her son by sending him to live with Gaius. He helped Hunith by hiding her lover, the Dragonlord Balinor from the wrath of Uther during the Great Purge. Hunith also seeks help from Gaius when Nimueh almost kills her.


Gaius had known Kilgharrah for at least twenty years and on at least one occasion he visited the Dragon for advice. Gaius respected Kilgharrah's power and wisdom but they weren't friends and Gaius was probably aware that Kilgharrah was desperate for his freedom.


At some point in the past, Gaius met the Witchfinder Aredian. He disliked Aredian but respected and feared his abilities as a Witchfinder and claimed he was a force to be reckoned with. Gaius greeted Aredian politely when they met but it was obvious that he disliked the Witchfinder. When Gaius was arrested for sorcery Aredian acted as his interrogator. However Gaius attempted to make a deal with Aredian to prevent Merlin and Morgana from being executed along with him. Along with Merlin he made fun of Aredian after he died, doing an imitation of him coughing up a toad.


At some point before the Great Purge, Gaius fell in love with Alice and they were even engaged to be married at one point. However the Great Purge forced them to seperate and they didn't see each other for approximately twenty years. They continued their romance when she returned to Camelot. However Gaius, blinded by love, was unable to realise that Alice was being controlled by a Manticore. When he did realise however, he continued to love Alice and Alice genuinely loved Gaius in return despite the influence of the Manticore. Gaius helped Alice escape from Camelot just as he had twenty years earlier. Merlin noted that Gaius could have left with her but Gaius had decided to stay in order to look after Merlin.


Gaius believed that basic problems should be solved by science. He was an excellent physician which has been proven on many occasions. However Edwin Muirden claimed his methods were "outdated", though this was possibly a lie to give Uther reason to appoint him as Court physician instead.

Gaius had a very broad theoretical knowledge of magic but when he used magic in series 1, he initially forgot the words (The Poisoned Chalice) or mispronounced the words (A Remedy to Cure All Ills). This shows that his magical skills have greatly decreased due to the many years he went without practice. The only successful time Gaius used magic in series 1 was when he created an antidote for Merlin when he got poisoned by Nimueh.

However Gaius's magical skills have clearly improved as the series went on. He used fairly strong magic when the goblin took over his body, though this was probably the goblins magic not his own.(Goblin's Gold) He later used magic to destroy a box that contained a Manticore, after luring the Manticore out of the box though he had to try three times before he succeeded. However it required powerful magic to destroy a Manticore's box, showing that Gaius had indeed grown stronger in magic. Gaius was even able to successfully attack Morgause, who was an extremely powerful sorceress, in order to protect Merlin, hitting her with a spell which sent her flying and stunning her long enough for Merlin to seriously injure and perhaps kill her, by throwing her into a pillar.

Gaius also had a talent for keeping secrets being able to hide a sorcerer, Merlin, right under the nose of Uther Pendragon, smuggle Morgause out of Camelot without Uther knowing until many years later and help Balinor and Alice escape Camelot (the latter individual twice). Gaius was also capable of hiding and avoiding attacks because he was the only person apart from Elyan to escape when an immortal army invaded Camelot. (The Coming of Arthur)

Kingdom of Camelot
Queen: Guinevere Pendragon
Court Physician: Gaius
Keeper of the Royal Library: Geoffrey of Monmouth
Knights: Sir Leon • Sir Percival • Sir Brennis • Sir Cador • Sir Geraint
Other Allies: MerlinAnnisOdinRodorMithianGodwynBayardElenaAlinedThe DiamairVivianOlaf
Former Allies: Morgana Pendragon † • Nimueh † • Cedric † ? • Cornelius Sigan † • Tristan de Bois † • Lady Catrina † • Edwin Muirden † • Uther Pendragon † • Agravaine de Bois †• SefaMordred †

Start a Discussion Discussions about Gaius

  • Is Gaius Merlins Uncle?

    10 messages
    • In that letter it definitely doesn't say Gaius is her brother. Just checked. "My Dear Gaius...." (signed) Hunith. And...
    • It seems like we'll never know for sure, but someone said that they (Gaius and Hunith) were step-siblings which seems plausible.
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