Overview
T'Pol is the first Vulcan officer to serve a prolonged term on a human vessel. The previous record was 10 days; by comparison, T'Pol served aboard the Enterprise for ten years (2151–2161). As a Sub-Commander serving the Vulcan High Command, she was stationed aboard the Enterprise in April 2151, as an observer to Captain Jonathan Archer and his crew, who the High Command insisted were not ready for interstellar space exploration. After the success of the Enterprise's initial mission led to the vessel being given an extended exploration mandate, T'Pol requested to stay aboard.
T'Pol remained aboard the Enterprise despite several attempts by her superiors to recall her to Vulcan. T'Pol's decision brought considerable scrutiny upon her from her superiors, and increasing support for her from her captain; she ultimately resigned from the High Command and accepted a field commission from Starfleet in 2154, resulting in her being granted the Starfleet field rank of Commander.
Originally viewed by her crew mates with resentment and suspicion, T'Pol has been forced to earn the trust of fellow officers, Commander Charles Tucker III being a particular focus of friction with her due to his perception of her being a spy for the Vulcans and their very different personalities. The character of T'Pol has developed from that of a "broken record" spouting the dogma of the Vulcan Science Council to that of a questioning scientific mind. Though she does not openly defy or reject the rulings of the Vulcan Science Council, her experiences on the Enterprise have proven to her that they can be wrong.
T'Pol is considerably more emotional than many other Vulcans and has always struggled to control her emotions, something that greatly concerned her mother. Her emotions became even more difficult to control following an exposure to trellium ore, a toxic substance which damaged the part of her brain responsible for emotional control. Nonetheless, T'Pol serves as an icon of Vulcan integrity. Her willingness to question the stale, self-serving decisions of her superiors (at least prior to the Kir'Shara incident), and her respect for Captain Archer position her at the fulcrum of human/Vulcan relations.
Throughout the entire Enterprise run, T'Pol only once said the trademark Vulcan greeting "Live long and prosper". With the exception of the episode In a Mirror, Darkly, T'Pol never rendered the Vulcan salute either.
Read more about this topic: T'Pol