Star Trek: Enterprise's central trio of Captain Jonathan Archer (Scott Bakula), Sub Cmdr. T'Pol (Jolene Blalock), and Cmdr. "Trip" Tucker (Connor Trineer) flipped the central trio of Star Trek: The Original Series in a weird way. The Star Trek: The Original Series prequel series depicted the early days of Starfleet, as the crew of the Enterprise NX-01 embarked on their first five year mission to explore strange new worlds. Perhaps to emphasize the connection with TOS, the human Enterprise Captain had a Vulcan as his second-in-command, but Archer and T'Pol's relationship was markedly different from that of Kirk and Spock.
Over the course of four seasons of Star Trek: Enterprise, Archer and T'Pol's relationship better reflected the spikier relationship between Dr. Leonard McCoy (DeForest Kelley) and Cmdr. Spock (Leonard Nimoy) in Star Trek: The Original Series. It was actually Trip and T'Pol who best resembled the close bond between Captain James T. Kirk (William Shatner) and Spock in TOS. Trip and T'Pol's relationship was more overtly romantic than Kirk and Spock's, but from the very early days of Star Trek: Enterprise, the human and Vulcan officers had a deep understanding and respect for each other.
Trip And T'Pol Were Enterprise's Real Kirk And Spock
In Star Trek: Enterprise season 1, episode 8, "Breaking the Ice", Trip accidentally intercepts a deeply personal correspondence between T'Pol and her betrothed. Trip's faux pas allows him to become closer to his frosty Vulcan colleague as they discuss her society's regressive approach to love and marriage. This would later complicate Trip and T'Pol's romantic relationship, when the time came for T'Pol to marry Koss (Michael Reilly Burke). Unlike when Kirk met Spock's fiancée, Tucker wasn't forced to engage in the kal-if-fee ritual to challenge the pending marriage, and instead suppressed his romantic feelings for T'Pol.
Like Kirk, Trip was often a rash and arrogant man who had a long romantic history. It was through his relationship with a Vulcan like T'Pol that Trip grew and matured, proving that it was much deeper than the controversial Star Trek sex scenes implied. T'Pol counseled Trip through his grief at the loss of his sister Elizabeth Tucker (Erin Taylor), and his grief at the death of Crewman Jane Taylor (Kipleigh Taylor). Like Kirk and Spock, death would come to define Trip and T'Pol's relationship, with the former taking Spock's role in Star Trek II: The Wrath Of Khan by sacrificing his life to save the ship in Star Trek: Enterprise's finale.
Captain Archer Became Like Star Trek: TOS' Dr. McCoy
Captain Archer was also sexually attracted to T'Pol, but his feelings manifested in a manner that shared more in common with Dr. Leonard McCoy's acerbic bantering with Spock. Initially, it appeared that Archer's distrust of T'Pol, and his harshness toward her was a side effect of the Vulcan problem in Enterprise. Archer saw T'Pol as another Vulcan who was holding humanity back from achieving its destiny as great galactic explorers, and treated her poorly as a result. It's similar to how Dr. McCoy's distrust of Vulcans often defined his attitude toward Spock, with both men never quite understanding each other's nuances, but still maintaining a close personal bond.
In the season 2 episode "A Night in Sickbay", it transpired that Archer's frustrations with T'Pol had a degree of sexual tension to them. He later apologized to T'Pol for his behavior, which substantially improved their relationship going forward. If Trip was Star Trek: Enterprise's Kirk figure, then it makes sense for Archer to fulfill the McCoy role, as both men were great friends had known each other for years. The way that Archer, T'Pol, and Trip played on audience familiarity with the TOS trio allowed Star Trek: Enterprise to push the franchise in a bold new direction, making everything new again.