A coup had led to the death of his father, Akaar. Capellan tradition permitted the new Teer, Maab, to murder Akaar's pregnant wife Eleen, to prevent the birth of the heir. Federation envoys Kirk, Spock, and McCoy objected, and in the resulting scuffle, escaped with Eleen to the nearby foothills. Maab and his forces pursued them, but a series of clever tricks enabled the Enterprise party to hold them off until after the infant was born. During this time, Kirk's courage and McCoy's medical skills won Eleen's admiration, which is why her son shared their names. Eleen eventually hit McCoy with a rock and escaped to join the pursuing warriors, telling them the Enterprise landing party was dead. Maab's aide Keel had moments earlier reported the location of the landing party, but Maab was prepared to accept Eleen's word. But their counterpart, Klingon agent Kras, forced a confrontation, creating a standoff between himself and the Capellans. In the resolution of that standoff, Maab died, and the position of Teer reverted to Akaar's infant heir. Eleen served as his regent. (TOS: "Friday's Child")
Several of the DS9 Relaunch novels set after the end of the televised Star Trek: Deep Space Nine run incorporate the Leonard James Akaar character; in them, he is a Starfleet Admiral. He and his mother were forced to flee Capella when he was a child, due to another uprising orchestrated by Keel, who had aided Maab in overthrowing Akaar's father. Akaar also appears in the Star Trek: Titan series, as well as in the DS9 relaunch novels Twilight, This Gray Spirit, Cathedral, Lesser Evil, and Unity.
In the Star Trek: Titan novel The Red King, it establishes that he was Captain of the USS Wyoming as of 2349 and has a previous working relationship with Tuvok that causes tension between them. Ben Gage, who played the elder Akaar in "Friday's Child", was also used to portray Admiral Akaar on the novel's cover.
An adult Leonard James Akaar, portrayed as the incumbent Teer of his people, also appears in #12, "Trial and Error!", of the second Star Trek comic from DC Comics. Here Samuel T. Cogley calls him as a defense witness in James T. Kirk's trial for crimes against the Klingon Empire.
In the computer game Star Trek Online, a much older Akaar appeared in the mission "Saturday's Child" as a Starfleet admiral negotiating with a primitive world for mining rights to their rich deposits of topaline.