"Any archer who wears the Yuyan tattoo can do that, your Highness. I can pin that fly to that tree a hundred yards away without killing it ... and I can do it blindfolded."
— Vachir bragging about his skills to PrinceOzai.
Vachir was a dishonored Yuyan Archer who was forced to resign from the elite force after failing then-PrinceOzai. Following these events, he became a member of the Rough Rhinos, where he served as their bowman. He specialized in fire arrows and his bow had a small torch just below the grip to ignite them. Vachir, along with the rest of the Rough Rhinos, was responsible for the deaths of Jet's parents and the destruction of their village. After the Hundred Year War, he stayed with the Rough Rhinos when they became a force for hire and ended up guarding Loban's iron mine at the Earthen Fire Refinery.
As a young boy, Vachir attended a Fire Nation school, where he was a star pupil under Ms. Kwan. He was taught discipline and hard work, which would help him in his later life.
As an esteemed member of the Yuyan Archers, Vachir was called to the Fire Nation Royal Palace by Prince Ozai, where he received the mission to travel to Hira'a and assassinate Ikem. Confident in his skills, Vachir accepted and left immediately. Many months later, the Yuyan Archer returned to the Fire Nation's palace to report to the prince that he had failed to locate and kill Ikem. Based on report of the local residents of the town, Vachir had traveled inside the Forgetful Valley and searched for Ikem, albeit with no success. Vachir concluded that no commoner like Ikem could have survived in the hostile environment and returned home. However, Prince Ozai was not pleased with his findings and commanded Vachir to return to Pohuai Stronghold to hand in his resignation to Colonel Shinu, stating that since he failed to complete Ozai's request, Vachir no longer qualified as an elite fighter, the best of the best.
Fighting the War as a Rough Rhino
Vachir did what he was told by the prince and left the Yuyan Archers, though he kept his equipment and uniform. Sometime later, he became a part of the Rough Rhinos, and as their resident archer, he and the rest of the group attacked the village where Jet and his family lived around 91 AG. In their attack, they killed his parents and destroyed the village, leaving Jet with a hatred of the Fire Nation for years to come. In late 99 AG, Vachir and his comrades invaded another Earth Kingdom village, forcing several inhabitants to become refugees, among whom were Tahn and his pregnant wife, Ying.
In 100 AG, the Rough Rhinos attempted to capture the Earth Kingdom's Chin Village in honor of Fire Lord Ozai. During this fight, Sokka reflected the sun in his magnifying glass to distract Vachir. Vachir turned and fired at the source of the light without being able to take aim properly. His arrows missed Sokka; instead they embedded themselves into Yeh-Lu's saddle bag which contained four sticks of dynamite. Yeh-Lu picked up the bag and threw it on the roof of a neighboring house where it exploded, burying Yeh-Lu under debris. While Vachir was still distracted, Katara sneaked up behind him and used her water whip to cut the saddle straps. Vachir fell off and was dragged by his fleeing rhino.
Later that spring, Vachir encountered Team Avatar with the Rough Rhinos at a small village; he and the Rhinos believed Sokka to be the Avatar and apprehended him instead of their true target. Even so, Aang, Katara, and Toph used their abilities to ward of Vachir and the Rhinos, forcing them to flee the village.
The Rough Rhinos ran into Iroh and Zuko, who had been branded traitors of the Fire Nation, not long after their final encounter with Team Avatar. Vachir shot a lit arrow at Zuko's back, but Zuko sensed the arrow, turned, and broke it apart as it approached him. Zuko then let loose a measured stream of fire which burned a hole in the archer's bow, a hand's width above the archer's hand. The blast passed through the bow and broke the string, leaving Vachir weaponless.
Guard at the Earthen Fire Refinery
After the Hundred Year War, Vachir and the rest of the Rough Rhinos became guards at the Earthen Fire Refinery. Along with Kahchi, he was stationed underground in an iron mine by Loban, which is where he encountered Katara and Sokka snooping around. He rapidly fired four arrows at the Southern Water Tribe warrior, which embedded themselves in a support beam, causing it to rupture and induce an earthquake as a result. Vachir did not relent his assault, however, and kept on firing at Sokka, until he found his bow entirely encased in ice, frozen to his arm, while his feet were also fused to the ground by Katara's waterbending attack. He eventually managed to free himself and prepared to attack again, though relented when the mine caved in and he became trapped.
As a Yuyan Archer, Vachir was very confident in his abilities almost to a fault, boasting to the then Prince Ozai that while any of his fellow archers could pin a fly to a tree from a hundred yards away without killing it, he could do the same while blindfolded.