In his youth, Alkar discovered that he had the ability to telepathically channel his darker impulses and negative emotions into other people, granting him unusual clarity of thought and leaving him free of distractions. This intense focus and the self-confidence it brought him made Alkar well-suited for a career as a diplomat.
But Alkar's success came at a cost. Maintaining his perfect peace of mind required him to establish a telepathic link with a "receptacle," a person who would serve as a vessel for all of Alkar's unwanted thoughts and emotions. The ideal candidate was another member of Alkar's species, as all Lumerians possessed some degree of telepathic ability, although other empathic races could also serve as substitutes.
Being the recipient of Alkar's "psychic waste" had a number of detrimental effects. His victims underwent radical changes in personality, the result of changes in their brain chemistry triggered by increased levels of neurotransmitters. They also became sexually aggressive, particularly regarding Alkar himself; they developed an obsessive fixation with him, could not bear to be apart from him for any length of time, and treated him very possessively, acting with hostility and even physical violence toward those whom they believed might "take" Alkar away from them. The most pronounced effect, however, was their greatly accelerated aging. Due to the terrible strain upon their bodies and minds, most of Alkar's receptacles survived for only a few years – some even less – and in the case of non-Lumerians, that length of time was shortened to a matter of days. When a receptacle inevitably died, Alkar would select another under the pretense of performing the Lumerian funeral meditation for the deceased person. Sharing this ritual with another person then allowed Alkar to establish a new telepathic link with them.
In 2369, Alkar was called upon to mediate a dispute in the Rekag star system. When his current receptacle, Sev Maylor, died – he had introduced her as his mother to explain her presence with him, although she was really a thirty-year-old woman – he turned to Deanna Troi to serve as the new vessel for his negative emotions. When his actions were discovered by Troi's shipmates, Alkar displayed no remorse and justified his actions by pointing out the services he performed for others as a mediator, forcing Captain Picard and Worf to leave the planet while he continued his work.
In an attempt to save Troi's life, Dr. Crusher was able to place her in a death-like coma, forcing Alkar to seek out someone else. He tried to use his aide Liva, but as Alkar was preparing to transfer his negative energy after severing his bond with Troi, Picard beamed Liva away. Overburdened by the emotions that he had long denied to himself, Alkar aged rapidly and died in a few moments, with Worf's security team witnessing his death when they entered his quarters. (TNG: "Man of the People")