Elaan possessed a formidable combination of qualities: considerable physical beauty, a position of high privilege and prerogative, and influence over the will of men (via Elasian tears). Her personality matched her gifts in their power – predominately expressed in her arrogance, sense of entitlement, disrespect for her perceived lessors, and an underlying loneliness.
In 2268, in a effort to bring peace between Elasians and Troyians, Elaan was arranged to marry the ruler of Troyius. The Federation, eager to facilitate peace in a region where Klingons claimed jurisdiction, assigned the USS Enterprise to transport Elaan to Troyius. Being necessary for Troyians to accept the marriage, Petri, a Troyian ambassador, was assigned to serve as Elaan's tutor in the polite manners of Troyian society.
As a proud Elasian warrior, Elaan was revolted by the prospect of marriage to a soft "Troyian pig." Kryton, leader of the Dohlman's guards, also hated the arrangement, as he loved Elaan and wished to marry her. Infuriated and insulted, Elaan raged about her circumstances and injured Petri by stabbing him in the back. The assault imperiled the success of the mission, after Petri refused to deal with Elaan any further.
Captain James T. Kirk assumed the role of the Dohlman's etiquette coach, but with little time in a diplomatic crisis, he refused to coddle her. When she behaved badly, he called her "an uncivilized savage, a vicious child in a woman's body. An arrogant monster!" Elaan answered by striking Kirk. He responded in kind, and later threated to administer an ancient Earth punishment, a spanking, if she continued to behave like a "spoiled brat."
Elaan was unused to defiance of her wishes, but impressed by Kirk's strength of will. With a growing attraction to the Captain, and in a last-ditch attempt to avoid a dreaded marriage, Elaan cried before Kirk, infecting him when he wiped a tear from her cheek. Immediately, Kirk became infatuated with Elaan. She told Kirk, "I chose you, and you chose me," and begged him to destroy the Troyians – offering him rule of the Tellun system in gratitude.
The power of Elasian tears was compelling, but events forced Kirk to deal with immediate concerns. The high stakes of his diplomatic mission, sabotage of the Enterprise dilithium crystals by Kryton, and a running battle with a Klingon battle cruiser served to bolster Kirk's resistance to Elaan's request, in spite of his continued feelings of love.
After the discovery of crude dilithium gems in Elaan's necklace allowed Kirk to fend off the Klingon attack, Enterprise arrived at Troyius. Elaan was finally resigned to her obligations and agreed to perform her duty. Emotionally wounded by the encounter, Kirk refused to witness the royal wedding ceremony. As a memento, Elaan gave Kirk her dagger, which Troyian custom would deny her. After she asked him to "remember me", Kirk answered, "I have no choice." (TOS: "Elaan of Troyius")