Jarth is one of the attendants travelling with the Lumerian mediator Ramid Ves Alkar aboard the Enterprise in Man of the People, part of the small party that accompanies him to the Rekag-Seronia peace talks.
Jarth appears in the sixth-season episode Man of the People. He is a member of the entourage of Ambassador Ves Alkar, a celebrated Lumerian negotiator whom the Enterprise carries to mediate the civil war on Rekag-Seronia.
Alkar's calm at the negotiating table depends on a secret: he channels his dark emotions into a chosen woman, a receptacle, who ages and sickens rapidly as a result. After the death of Sev Maylor, the old woman presented as his mother, he makes Deanna Troi his next victim. Jarth and his colleague Liva attend the ambassador throughout, apparently unaware of what the role of his companion truly involves.
Jarth is with Alkar on the planet when the Enterprise crew sever the link with Troi and the ambassador is destroyed by the emotions that rush back to him.