T'Rea was a Vulcan female alive in the early 23rd century. She was a Vulcan princess who would become the first wife of Sarek, and would later become a High Master of Gol. She was the mother of Sybok.
T'Rea and Sarek would mate only one time, which would result in the conception of their son, Sybok. Born in 2224, he was the first son of ambassador Sarek and T'Rea. The existence of this son was kept secret from Sarek, and T'Rea divorced Sarek when she ascended to the position of High Master of Gol. The marriage was annulled. (TOS novel: Sarek)
From a young age, T'Rea taught her son that emotions need not be suppressed but rather should be embraced. As a result Sybok grew up not believing the teachings of Surak; however, he hid this fact from other Vulcans. T'Rea believed Sybok would unite all religions by finding the source known as Sha Ka Ree. T'Rea often told her son the legend of Sha Ka Ree, which she had devoted her life to uncovering and had written an academic paper on. This single-minded focus on finding the Source consumed Sybok, who promised his mother that he would take her to Sha Ka Ree. Despite all the teachings of Sha Ka Ree, his mother did not reveal the location of this mythical paradise and kept to herself this knowledge, which she had learned from her time amongst the Ancients: the katras that were kept within the Hall of Ancient Thought.
The teachings of Sybok's mother were considered heresy, which eventually led to her stepping down from the position of High Master. This act meant that she was the least known of the High Masters of Gol; rather than be banished, she remained within the order though she was kept silent due to her beliefs. Eventually, she died and her katra was removed, placed within a vre'katra, and interred in the Hall of Ancient Thought. Sybok went to live with his father Sarek and his new family. It was at this time that Sybok met Sarek's wife Amanda Grayson and their son Spock. Sybok and Spock were raised as brothers. Sybok became well known as a particularly gifted young Vulcan, and it was widely believed that he would eventually take his place among the great scholars of Vulcan.
During his studies, Sybok received visions given to him by what he believed to be "God", beginning his quest for a place in Vulcan mythology known as Sha Ka Ree. When he was barely an adult by legal standards, he was determined in his course of action to find Sha Ka Ree. Sybok used the anger he had felt over his and his mother's treatment to fuel his actions, which he felt no regret in committing. Serving as a Watcher alongside Storel in their ceremonial role of guarding the Hall of Ancient Thought, Sybok violated the mind of the elderly Storel, leaving him damaged, in order to learn the layout of the Hall.
Entering the vast maze, he journeyed into the central chamber in order to find the vre'katra of his mother T'Rea. Finding the receptacle, he mind melded with it despite the risk of succumbing to madness. There he learned of the rumored location of Sha Ka Ree within the Great Barrier. He planned to place the mind of his mother within his own in order to carry it to the Source. However, when he was confronted by High Master T'Sai along with two adepts he lost contact with the mind of T'Rea. Angry, Sybok believed T'Sai had silenced his mother only to learn from the High Master that T'Rea had willingly accepted true death rather than be interred within the Hall once again. Sybok's actions were considered a heinous crime in his society which led to him being declared Ktorr Skann: an outcast from his people who was exiled from the Mother World. (TOS novelization: Star Trek V: The Final Frontier)