S'yito was a Yuuzhan Vong male and a member of the warrior caste. During his species' invasion of the galaxy, S'yito was assigned to the prison planet Selvaris, holding the rank of subaltern. Although a subordinate of the penal colony's chief officer, Malik Carr, S'yito nevertheless oversaw much of camp's affairs, devoted as he was to his position. He took time to attempt to understand the prisoners under his care, and learnt to speak fluent Basic.
As well-versed as he was in their language, S'yito was often derided and fooled by the prisoners, most notably when Galactic Alliance veterans Pash Cracken and Judder Page joined the body of captives and organized a successful prison breakout. S'yito's guards pursued the four captives who managed to escape the Selvaris camp, but failed to prevent one, a Jenet, from vanishing off-world with vital data. Commander Carr had S'yito's warriors punished for their failure, although the Subaltern himself was spared execution. On the commander's orders S'yito took a group of warriors to execute those in the surrounding villages, who were thought to have aided the escapees.
The Yuuzhan Vong male S'yito served in the Warrior caste. During the Yuuzhan Vong War, a conflict that affected the entire galaxy, S'yito went to Selvaris, located in the Tantara system in the Inner Rim, with the disgraced former commander, Malik Carr. Carr had been demoted and dispatched to Selvaris, an isolated backwater, following the disaster sustained by his forces at Fondor. Although the former officer was in overall command of the prison, it was S'yito who oversaw the internal regulation of affairs in the penal colony, which had been set up to house prisoners for their eventual use as sacrifices in grand ceremonies. The Subaltern entertained the notion that the captives being collected at the camp—including several notable enemies following the failure of the Galactic Federation of Free Alliances's Operation Trinity—should have been executed. S'yito believed that the fact that a full complement of warriors were required to guard a world such as Selvaris was proof that the invasion was floundering. Still, S'yito maintained a keen interest in his enemy. He learned Galactic Basic fluently, mastering the language of the infidels almost as well as Malik Carr himself. He became well acquainted with the customs and routines of the prisoners, guarding the captives as they worked, often drawn into debates with them. On one occasion, as the prisoners grudgingly threw their dead into a maw luur, S'yito expressed his disbelief at the idea that the captives still did not understand that the Yuuzhan Vong worshiped pain and death on behalf of their gods. Daubed head to toe in blood, as was the custom of many Yuuzhan Vong, S'yito made a point of demonstrating the intractable situation of the infidels by snatching from the air a small native insect, and crushing it against his chest.
S'yito believed that the complaints put forward by the prisoners on Selvaris—that they could not stomach Yuuzhan Vong food—were false; a means by which he could be antagonized. Commander Malik Carr, however, had ordered that food be brought in from the surrounding settlements, and it was in this way, weeks before the reshaped galactic capital was liberated from S'yito's people, that the prisoners under his charge received the impetus to stage a break-out. On one hot day, a Ryn came from one of the settlements bearing food; S'yito and his lieutenants searched the supplies, but did not find anything amiss; the Ryn in fact disarmed the Subaltern's suspicions slightly by speaking of his faith in Yun-Yuuzhan, and referring to S'yito as "Fearsome One", an honorific reserved for commanders. S'yito allowed the Ryn to enter, unaware that the food-bearer was carrying vital information in a holowafer, and was a member of his species' intelligence network. During the captives' lunch hour, S'yito was on patrol while Judder Page, Pash Cracken, Thorsh and several other captives found the Holowafer in their food and had four of the prisoners commit the binary code inside the wafer to memory. However, S'yito was alerted that something may have been amiss by the fact that a sabacc game, staged as cover for Cracken and Page while they examined the holowafer, was taking place during the midday meal hour. With his guards, S'yito burst into the eating shelter, demanding answers. Page merely mocked the Subaltern until S'yito left, unsuccessful in determining the cause of the unusual behavior.
Hours before sunrise, the prisoners staged their break-out. Three Bith and the Jenet Thorsh left through a secret tunnel and escaped on swoops hidden by the same Ryn months earlier, with the vital data for the Alliance command memorized. The prison camp's guards soon began the chase, some flying in coralskippers, some on Tsik vai, others on foot with bissop hounds to track the prisoners. Only one prisoner, Thorsh, eventually made it to freedom. The surviving Bith was brought back to the camp, where Malik Carr awaited with a furious S'yito, along with the guards and the prisoners. Page, Cracken and the others were forced to assemble in the midday sun, and watched as S'yito dragged the Bith out before them and dumped the wounded alien in the sand. Before the Bith could be punished, Commander Carr ordered that, as punishment for their failure, six of S'yito's warriors should execute the other half-dozen present; the slain were randomly chosen, though S'yito, other than giving the order, was uninvolved. The Subaltern watched as Carr interrogated and choked the Bith to death with a tkun. Carr ordered S'yito and his men to escort the prisoners to an immolation pit which had been dug outside the prison walls; there, Carr ushered the captives into its stifling depths. S'yito was then told to take a complement of his guards and slaughter everyone in the surrounding villages for their complicity in the break-out.
S'yito was shrewd and able, but failed to appreciate the spirit and courage of his prisoners, or ultimately understand them. He believed strongly in the religion of his species, but held no great enthusiasm for the indoctrination and subjugation of those he considered infidels; he felt that the prisoners should have been executed, and claimed that there was no "middle way" between being a Yuuzhan Vong or being dead. S'yito held no regard for the lives of those who were not of the Yuuzhan Vong, but was also restrained, silent and understanding as Malik Carr ordered the death of several of his guards. The loyalty and devotion to his life as a warrior allowed him to act violently and without remorse, though S'yito harbored a desire to see himself escalated beyond his position.
Subaltern S'yito appears only in the opening chapters of James Luceno's The New Jedi Order: The Unifying Force, published in 2005. The novel served as the final installment of The New Jedi Order series.