Christine Chapel was a nurse aboard the USS Enterprise, under the command of Captain James T. Kirk in 2266.

Chapel had abandoned a career in bio-research for a position in Starfleet, in the hopes that a deep-space assignment would one day reunite her with her missing fiancé Dr. Roger Korby, a scientist of reknown.

By 2266, Chapel was a commissioned junior lieutenant and assigned to the USS Enterprise, serving as head nurse under Enterprise Chief Medical Officer Dr. Leonard McCoy.

On Stardate 2712.4, the Enterprise found Korby , exploring and exploiting a sophisticated android manufacturing technology, the legacy of a long-dead civilization. Korby had replaced his own damaged body, transplanting his personality into an android replica and built himself a beautiful companion, Andrea. After exhibiting his madness, the android Korby was destroyed. Chapel then elected to remain with the Enterprise throughout the five-year mission.

Even while she still sought to locate Korby, Chapel was deeply infatuated with the Enterprise's half-Vulcan science officer Spock.. While her attraction never interfered with her professional duties, it was an ongoing source of tension and bemusement throughout the five-year mission.

Initially, Chapel kept these feelings to herself. However, when the Psi 2000 intoxication afflicted the crew of the Enterprise, Chapel admitted her love for Spock, who was shocked:

Chapel insisted that Spock address her by her first name, as opposed to her title, which he resisted. Chapel was unaware that Spock's inability to react to her emotionally was further complicated by his betrothal to T'Pring. Leading him to the ceremony in which his fiancée rejected him in favor of a different suitor, Spock underwent a period of intense emotional outbursts: a blood fever known as pon farr. Chapel characteristically doted after the Vulcan, preparing plomeek soup, a traditional Vulcan broth. The experience allowed them to discuss, even if briefly, Chapel's confession of love. Despite his acknowledged inability to return her affections, he did refer to her as Christine for the first time.

Chapel's longing for Spock was well-known among crew members, and noted openly by Captain Kirk and Dr. McCoy on a number of occasions. During Spock's recovery after a near-death experience on Neural, fellow medical officer Dr. M'Benga caught Chapel tenderly holding Spock's hand while watching his recovery on the medical panel atop his bed.

Later Career
Doctor Chapel in 2272
Commander in 2286

By late 2269, Chapel had been promoted to the rank of lieutenant. She had the Starfleet serial number NI-596 MT21Z.

When under the influence of the women of Taurus II, the male crewmembers of the Enterprise were incapacitated by the siren's song. Lieutenant Uhura took command of the vessel, and assigned Chapel to acting chief medical officer. They led a landing party down to the planet's surface to rescue Captain Kirk, Spock, and Dr. McCoy.

In 2269, Chapel obtained a love potion from Harry Mudd, and she used it on Spock. Temporarily, Spock obsessively longed for Christine.

When in miniaturized state, Chapel assisted Dr. McCoy mend Hikaru Sulu's broken leg; as she attempted to retrieve a microscope laser, she tripped into the lab fish tank and nearly drowned, before she was saved by Captain Kirk.

At some point prior to this, Chapel had acquired a titanium bracelet made by the metalsmiths of Libra, which she would occasionally wear while on duty.

When Captain Kirk and Spock mutated into water-breathers, Chapel assisted Dr. McCoy in reversing their mutations.

Following the Enterprise's five-year mission of exploration, she was able to complete her medical degree. Chapel returned to the Enterprise at the end of its refit as chief medical officer.

Upon the return of Dr. McCoy during the V'Ger crisis, he explained to Kirk that he was "going to need a top nurse not a doctor who will argue every little diagnosis with me." Chapel later performed medical scans on the Ilia probe, and assisted in reacquainting the probe with Ilia's former life. see Star Trek: The Motion Picture

According to the TMP novelization, she was supposed to be the Enterprise's chief medical officer, but the arrival of McCoy changed that and Chapel was very pleased that he was CMO and not her.

By the latter half of the 2280s, Chapel held the rank of Commander.

In 2286, she was stationed at Starfleet Headquarters, where she coordinated relief efforts while Earth was suffering a severe ecological "attack" from an orbiting space probe. see Star Trek IV: The Voyage Home