Yoponek, whose full Chiss name was Coduyo'po'nekri and whose core name was Yoponek, was a male member of the Coduyo family. He was also engaged to Yomie. His academic focus was history.
Before completing their education, he and Yomie took a wandering year, opting to journey throughout the Chiss Ascendancy. During their travels, they crossed paths with Haplif of the Agbui, who was attempting to study the Chiss with the goal of instigating a civil war. Haplif offered them passage on his starship, claiming it would save them money and provide guidance to the Agbui, but his true intention was to gather intelligence about the Ascendancy.
Yoponek became engaged to Yomie at some point. During their wandering year, the couple encountered Haplif of the Agbui at a Chiss festival. As Yoponek and Yomie were interested in exploring the Ascendancy and were running short on funds, Haplif proposed that they act as cultural guides for the Agbui in exchange for free travel on the Agbui ship, which was also traveling across the Ascendancy. However, the Agbui were secretly plotting to incite a civil war within the Chiss Ascendancy and intended to exploit Yoponek's ambition to climb the ranks of Chiss society. After Haplif gifted Yomie a nyix brooch, the Chiss couple accepted the offer.
Five weeks later, Yoponek informed Haplif about an ambitious Councilor from the Xodlak family on Celwis, Xodlak'uvi'vil (Lakuviv). Recognizing Lakuviv as a potential means to infiltrate the Great Families of the Chiss, Haplif encouraged Yoponek to meet with him, suggesting that he would be meeting a significant Chiss historical figure before his rise to prominence. While intrigued, Yoponek was concerned about Yomie's desires. Haplif wanted to visit Celwis immediately, but this would disrupt Yomie's plans to visit Shihon for the month-long Grand Migration. Yoponek attempted to persuade Yomie, arguing that it was unreasonable to expect the Agbui to remain on Shihon for an entire month, but she remained steadfast.
The Agbui traveled to Shihon, but over the course of three days, Shimkif worked to disrupt and prematurely end the migration. On the fourth day, Yomie and Yoponek returned to the ship a mere two hours after departing. Yomie was greatly frustrated by the situation, while Yoponek, though concerned for her, felt a sense of relief. Haplif suggested going to Celwis, which piqued Yoponek's interest. However, Yomie discovered other migrations on Shihon that she wished to witness. Yoponek again tried to reason with her, pointing out the unreasonableness of making the Agbui wait on Shihon for such an extended period. Eventually, Yomie and Haplif agreed to stay on Shihon for a few more days before heading to Celwis. Four days into the Panopyl Mountains migration, Yomie began to feel unwell, and on their return to the Agbui ship, she became unable to walk. Upon returning to the ship, Yoponek informed Haplif of her condition. Chiss medics arrived and determined that she had been poisoned by the venom of a greenstripe, which was, in fact, Shimkif's doing. The following day, Yoponek went to the migration viewing grounds alone. During his absence, Yomie discovered that the Agbui's touches were actually a means of expressing their telepathic abilities. When Yomie threatened to reveal the Agbui's manipulation to Yoponek, Haplif was forced to kill her. Upon Yoponek's return to the Agbui ship, Haplif falsely claimed that Yomie had decided to temporarily separate while he and the Agbui went to Celwis to meet with Lakuviv. After some persuasion, Yoponek believed the lie and eagerly anticipated the trip to Celwis. Haplif further solidified Yoponek's resolve by giving him Yomie's brooch, claiming it was her promise that they would be reunited. On the way to Celwis, Yomie's body was discarded into interstellar space.
Upon arriving at Celwis, Yoponek and Haplif met with Lakuviv at Redhill Hall. During the meeting, Yoponek and Haplif requested that the Xodlak family provide a small plot of land for the Agbui to cultivate their spices. Haplif also presented Lakuviv with his own pair of nyix brooches, secretly hoping that the Xodlak family would take notice of the metal and inquire about its origin planet. Lakuviv and his Senior Aide, Xodlak'ji'iprip (Lakjiip), located and temporarily granted the Agbui a plot of land owned by Xodlak yubal rancher, Xodlak'phr'ooa (Lakphro). Over the next few weeks, Yoponek dedicated his time to networking and conversing with as many Xodlak family representatives as possible. Soon after, Yoponek was invited to a meeting between Lakuviv, Lakjiip, and Haplif. Over the preceding weeks, Lakuviv and Lakjiip had been manipulated into believing in the existence of an unclaimed nyix mine on the planet of Hoxim. Haplif further manipulated Lakuviv into dispatching a Xodlak defense force to claim the planet. During the meeting, Lakuviv mentioned that Xodlak reservists would likely be called upon to staff these Xodlak defense ships. Recognizing this as inefficient, Yoponek suggested utilizing the Chiss family emergency protocols, explaining that Chiss families reserve the right to summon any active-duty Defense Force or Expansionary Defense Fleet officers to staff family ships during an emergency. Lakuviv thanked Yoponek for the suggestion.
Later, Shimkif sent Yoponek on an errand before abandoning the Chiss Ascendancy. He was subsequently questioned by Celwis Xodlak Patriel Xodlak'oo'nifis (Lakooni) regarding his involvement with the Agbui.
Yoponek possessed significant ambition in his political career, actively seeking to network with mid- and high-ranking officials from other Chiss families. Haplif exploited this characteristic to orchestrate a meeting with Councilor Lakuviv on Celwis.
Yoponek's first appearance was in the 2021 novel Thrawn Ascendancy: Greater Good, authored by Timothy Zahn.