Born 200 years prior to Adron's Disaster, Fentor was from a poor family and so became a mercenary in the Army of the Three Spears, where he showed some aptitude with the training of Teckla recruits. After the disaster, Fentor served in the army of a warlord bent on expanding his holdings, where he gained some additional experience commanding small units in battle. However, after some years this warlord was defeated by an army commanded by Suura. Escaping this defeat, Fentor was drawn to Morrolan's camp during the ground--construction phase of Castle Black, likely in response to the circle of witches pyschic call designed to attract warriors. When Morrolan learned that Fentor had some experience with training soldiers, Fentor was promptly promoted to Sergeant and put in charge of working with the new recruits.
As Morrolan's army gradually grew, Fentor continued to train them until they were a force "just close enough to ready to permit itself to receive some amount of slaughter before dissolving utterly." Fentor advised Morrolan on matters military, and it was Fentor's shrewd questions to a new Teckla recruit that alerted them to the alarming proximity of Skinter's armies. Fentor and Morrolan had frequent arguments over tactics, defensive fortifications, and the like, but Morrolan grudgingly acknowledged Fentor's superior body of military experience, while Fentor gradually came to appreciate Morrolan's budding military genius. Fentor was also promoted regularly as Morrolan's army, although still modest, grew in size.
Fentor played a key role in the restoration of the empire, serving as military advisor to Morrolan in the frequent battles with Skinter's army that characterized this period. He also later led Morrolan's division during the Battle of Adrilankha--Morrolan being otherwise occupied at the time. (See Tri'nagore)
Fentor is currently the head of security at Castle Black, where he is aided by Vlad Taltos. One one occasion, he was lured away from Castle Black and killed during a plot to assissinate Morrolan, but he his body was discovered and revivified in time.
Fentor apparently resembles, to some degree, a Tsalmoth, and has occasionally been mistaken for one.