In the 2250s, rebels allied with the Klingon Empire killed Geror and took Arlph hostage. The starship USS Republic responded to Federation calls for help, and a young James T. Kirk was in charge of the one of the landing parties. Kirk's team located Arlph, but during the rescue attempt, Kirk's weapon discharge ricocheted into Arlph, rendering him comatose for the next several years. As he was incapacitated, his younger brother rightfully assumed the throne.
After Arlph recovered, he was no longer considered an heir, and in accordance with Yannid VI law he took the name Phral and joined the diplomatic service. By 2273, he had risen to the rank of ambassador, and had amassed some wealth despite serving as a diplomat.
In 2273, the starship USS Enterprise arrived to convey Phral to the official signing ceremony that would admit Yannid VI to the Federation. Phral was stabbed and killed, seemingly while beaming aboard.
In actuality it was a hoax. Phral conspired with the rebels in order to implicate Kirk and derail the signing. Phral's transporter beam had been slyly intercepted, and the Enterprise actually beamed up the body of a surgically-altered lookalike who had been killed ten minutes earlier. Afterward, Doctor Loroc used cosmetic surgery to alter Phral's appearance. When Kirk, Spock and Leonard McCoy investigated Loroc, Phral killed her, but his plot was exposed and he was apprehended. (TOS comic: "The Enterprise Murder Case!")