Hreven Karsh, belonging to the Yuuzhan Vong's warrior caste, rose to the rank of commander during the Yuuzhan Vong War. This escalation occurred after his kinsman, Supreme Commander Komm Karsh, met his end. Hreven Karsh later joined B'shith Vorrik, another supreme commander, in a campaign aimed at destroying the Imperial Remnant. Subsequently, he received orders to stay in the Unknown Regions and pursue a group of Jedi searching for the living planet of Zonama Sekot. His failure in this endeavor led to his return to Coruscant, where Supreme Overlord Shimrra Jamaane rebuked him and assigned him a suicide mission: invading the Chiss Ascendancy.
After Supreme Commander Komm Karsh, the leader of the Yuuzhan Vong's only strategic reserve fleet, was defeated and killed along with his fleet at Obroa-skai, Hreven Karsh was soon escalated to take his deceased relative's place. Green and overzealous, Hreven Karsh went with Supreme Commander B'shith Vorrik on the mission to eliminate the Imperial Remnant's threat. When Vorrik's assault was halted at Borosk, Hreven Karsh was sent to the Unknown Regions to track Jedi Master Luke Skywalker and his search party. However, he lost track of the Jade Shadow and the Widowmaker, Skywalker's task force ships, near the Chiss Ascendancy's borders. With his escalation wounds still open and bleeding, Hreven Karsh went back to Supreme Overlord Shimrra Jamaane on Yuuzhan'tar, once known as Coruscant.
Karsh reported to the Supreme Overlord in the Hall of Confluence and faced the Dread Lord's wrath. The commander said he hadn't wanted to trespass on Chiss territory and had only been "combing" the Ascendancy's borders to find the Jedi. Jamaane ordered Karsh to take what the Yuuzhan Vong deserved and remind the Chiss of who ruled the galaxy. When Karsh swore in the name of Domain Karsh that he would capture the Jedi fugitives, the supreme overlord took him at his word. He swore that he would execute every member of Domain Karsh if the commander failed. Nom Anor, a distant Yuuzhan Vong outcast, watched Hreven Karsh's audience through a hidden villip and saw it as a pointless gesture by Shimrra—the Chiss would be provoked, and commander Karsh would be lost. Before the doomed commander left the Hall of Confluence, Jamaane demanded Karsh's hand as a reminder of their agreement. Hreven Karsh severed his hand—Onimi, Shimrra's familiar, took the limb away—and left the supreme overlord's presence, bleeding heavily, with orders to lead a suicide mission into the Chiss Ascendancy.
Hreven Karsh's membership in Domain Karsh connects to Walter Jon Williams' The New Jedi Order: Destiny's Way, the novel where Hreven's relative, Supreme Commander Komm Karsh, dies. Hreven Karsh's fate is never revealed in the final two books of the Force Heretic trilogy, but he most likely dies, as both Shimrra and Nom Anor expect, fighting the Chiss.