Alator

Alator of the Catha is both a warrior and a High Priest of the Old Religion. His formidable magical powers make him a powerful ally.

History
Alator said he had had magic all his life, and because of it he had been persecuted, chased, and hunted all over the five kingdoms. Eventually, he and his guard found their way to a city, where he was later found by Morgana. In exchange for her healing bracelet, Morgana asked him to kidnap and torture Gaius to find out who Emrys really was.

He and his companion then sneaked into Camelot and with the help of Agravaine, kidnapped Gaius. They took him to the old iron mines, where Alator tortured Gaius using a magical art (the mental torture) only known by the Catha.

Eventually he caused Gaius to snap, and the old physician revealed that Emrys was Merlin. He also mentioned Merlin's destiny, in which he would bring magic back to the realm and help to create Albion. Realising who he was facing, Alator switched sides. He saved Merlin from Morgana, and revealed how he and many others had dreamt of what Merlin and Arthur were trying to build. He said he was honoured to be in his presence, and attested to how he and many others would gladly die for him.

Afterwards, he departed and returned the healing bracelet to Morgana, which she found after she had regained consciousness (The Secret Sharer).

Personality
Although at first Alator appeared to be cruel and sadistic, he was actually a very honourable man, though he was willing to use torture to get information if he felt it was necessary. He showed no discomfort about torturing Gaius but nevertheless protected Merlin from Morgana and told the young sorcerer that he was honoured to be in his presence and would gladly die for him if necessary. Because he chose to save Merlin, it is possible that Alator regretted torturing Gaius after learning that Merlin was in fact Emrys.

Apparently Alator did not know of Emrys before Morgana asked him to find out who he was because he switched sides after he learned who Emrys was. Presumably he originally thought that Emrys was not an important sorcerer, merely one who was an enemy of Morgana, and it was only after Gaius revealed his identity that he realised Emrys was actually destined to be the most powerful sorcerer who had ever lived. He had heard of the destined Albion but didn't seem to have heard the name Emrys previously - it was afterall the name used by the druids who are very secretive.

Abilities
A warrior as well as a High Priest, Alator was shown to be a powerful sorcerer. He created a ring of fire and mentally tortured Gaius. He was also able to knock Morgana out with a single stunning spell, something even Merlin achieved to do only on his third effort in his aged form.

Just the fact that he was a High Priest of the Old Religion may indicate how much power Alator had. The Catha could also apparently sense the power of Morgana's bracelet, much like Merlin could with The Cup of Life.