Taim has black hair, is above average in height with a dark face, tilted eyes, hooked nose and high cheekbones of a Saldaean. When introduced to Rand al'Thor he is judged to be around thirty-five, but Jordan has subsequently confirmed he is in his late twenties.
Taim can channel Saidin, the male half of the One Power and declared himself the Dragon Reborn. During the events which unfolded during The Great Hunt and when Rand al'Thor declared himself the true Dragon, Taim was thrown from his horse in battle and was captured by Aes Sedai. He escaped and now leads Rand al'Thor's male channelers, the Asha'man, and calls himself the M'Hael, which means Leader in the Old Tongue. He is notably arrogant, forgoing normal Asha'man ranking markers for blue-and-gold dragons on his coat sleeves, paying homage to Rand's arm markings while apparently mocking him at the same time.
Taim came to Rand in Caemlyn shortly after Rand announced an amnesty for men who could channel, carrying one of the seven seals on the Dark One's prison. He was pursued by Davram Bashere, who became one of Rand's highest generals. For all the speculations of his treachery, Taim turned the Black Tower from a small farmhouse with around a dozen men into the powerhouse of the One Power that it is.
Although it hasn't been entirely confirmed, Taim is most likely a Darkfriend; he secretly sent four Asha'man (Charl Gedwyn, Manel Rochaid, Peral Torval, and Raefar Kisman; all Darkfriends) to kill Rand near the end of The Path of Daggers. During Winters Heart it is revealed that all the above men were ordered by both Taim and Moridin to kill Rand, two of them are killed in Winters Heart. It should also be noted that he is at odds with the Asha'man Logain, also a former False Dragon, who holds more loyalty to Rand than Taim does. References made in The Dragon Reborn may also suggest that Taim was converted into a Darkfriend by a circle of thirteen sisters channeling through thirteen Myrddraal.
In Knife of Dreams, Taim met with the White Tower Aes Sedai and agreed to allow the bonding of Asha'man by sisters of the Red Ajah. His justification for this was to "Let the Lord of Chaos rule," a phrase unknown outside the circle of the Forsaken and high-ranking Darkfriends (further evidence that he is a Darkfriend or a new Dreadlord).
Logain claims that Taim has a small sect of followers, most likely Darkfriends as well, whom he personally teaches weaves that no other Asha'man know. Taim refuses to believe that Rand was responsible for the cleansing of saidin.
Taim is a very power-hungry individual, as evidenced by his claim to be the Dragon Reborn. He is spiteful of those more powerful than he, but is willing to become their underling if in exchange for a position of his choosing. This is what led to his dissension with Rand. He seems at first very willing to be second to Rand, but with a title and power of his own choosing, which Rand is unwilling to allow. Taim first begins to resent Rand when he places him in the farm, from which the Black Tower would spring, to teach commoners who sought to learn to channel, instead of allowing him to stay by Rand's side. When Rand confers upon him the title of Asha'man, he is clearly unhappy about being seen as second to him, and after that day never wears the black garb of Asha'man, nor the Sword pin of the Dedicated or the Dragon pin of the Asha'man, instead electing garments adorned on the sleeves with Dragons, to make himself seem equal to Rand. The two are at silent war with each other: Rand is unable to kill him despite his treacheries because he is holding the Black Tower together for him to use at Tarmon Gai'don, while Taim cannot risk trying to kill Rand personally because Rand is more powerful than he, and any open action against him could turn Asha'man who are loyal to Rand against him.
He is very powerful in the Power, but it is not known just how strong he is. Initially he is far more experienced in using the One Power than Rand which means he has a certain advantage there, even if they are otherwise pretty much matched in talent. In Lord of Chaos, Rand tells him to seize as much of the Power he can. Taim seizes the Power and Rand sees that he holds almost as much as Rand is able to. However, Rand doesn't detect any evidence of strain on Taim's part, which causes Rand to suspect Taim is more powerful than he lets on.