Around 15 ABY, Karr Nuq Sin, a human, was born to Tomar and Looway Nuq Sin on Merokia. Merokia is a desolate [desert](/article/desert] planet situated near the Unknown Regions. The Nuq Sin family, who were middle-class [tailors](/article/tailor], hoped that their son would follow in their footsteps and master the craft. Little did Karr know, he also possessed Jedi heritage through his great-grandfather, Naq Med, a former Jedi Padawan. As a child, Nuq Sin shared a close bond with his paternal grandmother, J'Hara. He attended a school on Merokia, but he was a solitary figure who struggled to form friendships with his classmates.

His life underwent a dramatic transformation at the age of thirteen in 28 ABY, when he began to experience severe headaches and seizures upon touching certain objects. These seizures were accompanied by distorted visions of events from the past. Nuq Sin's parents feared that their son was suffering from a brain tumor or another serious medical condition, so they sought the advice of several doctors, including the leading expert in the sector. However, none of these medical professionals could find anything wrong with the boy. In contrast to his parents, Nuq Sin's grandmother, J'Hara, who was familiar with the Jedi Order and the Force through her father, believed that his episodes were not indicative of an illness. Instead, she believed they were a sign that he was Force-sensitive and possessed the ability to learn about an object's history by touching it. While Tomar and Looway pursued medical treatment for their son, J'Hara attempted to assist him by instructing him in the ways of the Jedi and the Force. She believed that through these studies, Nuq Sin could gain greater control over his abilities and find relief from his headaches. J'Hara suggested that by finding Jedi objects and using his power to see their history, he could learn how to use his ability properly and how to become a Jedi. As a short-term solution, she also crafted a pair of leather gloves for him to wear in order to avoid episodes from accidentally touching an object that induced visions.

Following the manifestation of his powers, Nuq Sin constructed a droid called RZ-7 by combining the circuitry of a protocol droid, the hard drive of an astromech, and the outer casing of a medical droid. Although nominally a medical unit intended to aid him with his seizures, the droid primarily functioned as a protocol droid and could also perform other tasks, such as driving a speeder. Nuq Sin's true motivation for building "Arzee-Seven" was to have a friend. During this period, Karr continued to struggle with his school life and had few friends aside from his droid. He was also subjected to bullying, including an incident where a Zabrak boy broke his model B-class X-wing. He was constantly belittled by the Besalisk Royke and his cronies, who taunted him for his health issues and his belief in the Force. He was deeply unhappy at school and considered it his least favorite place in the universe.

After Karr attempted to use the Force choke on Royke, he was taken to the headmaster's office and made to wait outside while the bully was immediately taken to see the headmaster. While waiting on a wooden bench, Karr decided to add his own name to the numerous carvings that other students had made on the bench. He had barely added the first letter of his name when Kragnotto, the Ankura Gungan teacher in charge of the science program, dragged a highly resistant student into the room and forced her to sit down. She had been rummaging through his belongings, and he intended to have her punished, leaving the two alone on the bench. The girl, Maize Raynshi, noticed Karr's act and mocked him for his rebellious attempt to carve his name into the bench. They formally introduced themselves to each other, and during their subsequent conversation, Maize expressed her belief that the Jedi were not real and that she did not believe in his ability to see visions from certain objects that he touched. When he insisted that he was telling the truth, she challenged him to see something on one of her father's tools, which she kept in her bag. However, after holding it and experiencing a vision, Karr passed out.

When he regained consciousness, he was surrounded by Maize, the Ovissian headmaster, Royke, and others. After a moment of confusion, Karr was helped to his feet and convinced the headmaster to allow him to contact his medical droid, RZ-7, and to go home early. Maize offered to wait outside with him for the droid, and the two left to wait outside of the school, although Royke complained bitterly about Karr not receiving detention. While they were waiting, a Togruta student teased Karr and said that people were saying he was dead, but the student ran off after Maize shouted something rude in Huttese about his parents. Maize then revealed that her father, who worked for the [First Order](/article/first_order], had had some dealings with the Hutts and that she considered their language to be perfect for swearing. When RZ-7 arrived, Karr became embarrassed as Maize had to sit on his lap because the family speeder was only a two-seater. While riding back to Karr's house, Karr revealed to her the truth about RZ-7. Then, after a brief disagreement about the Jedi that continued their conversation from the bench, Maize expressed interest in meeting Karr's grandmother. He was forced to shout over the speeder's engine that she had passed away.

When they reached Karr's house, he and Maize headed inside, although they were briefly stopped by his older brother, Trag. After Karr identified Maize as a friend, Trag shrugged and allowed the two to continue on their way to Karr's room. Once there, Maize expressed surprise at Karr's collection of objects, and he explained several of his pieces to her, including a broken staff with a silver top from which he claimed to have received a vision. Maize and Karr continued to argue about the Jedi before Karr brought the discussion to an end by asking if she wanted to learn what he had seen in the vision gleaned from her father's tool. She sat down, ready to hear his vision. He explained that he had felt that the tool had been part of something big, and that many stars and so much darkness that it was like death was also what he sensed. Maize retorted that he was reaching and sounded like he was claiming it came from the Death Star, which he denied and stated that everything was cold, covered in ice and snow. He plowed on, moving on to Maize's father and describing how the man had blue eyes, looked younger than people thought he was, had on a grey suit, and that he was human. Karr used that information to confirm that Maize was only half Mirialan. Maize appeared stunned and admitted that it was either impressive or a very good performance.

The next day at school, Karr was called to the headmaster's office during his second-period calculus class, not knowing what it was about as his Givin teacher's mumbled statement was cut off by the door closing. When he reached the office, he found his parents Tomar and Looway waiting for him along with the headmaster. They proceeded to explain to him that they had received test results back from a Chandrilan specialist who had examined him a month earlier. These results revealed that Karr apparently had a weak constitution and that all of the stress he was experiencing at his current school wasn't healthy for him. So, his parents and the headmaster arranged to have him transferred to a trade school in Taeltor Province located across the planet where his uncle would look after him. Karr protested and grew angry that none of them believed that he was Force-sensitive, but also because he perceived them as thinking he was weak and that because he was special, he was being treated differently. Despite his parents' protests against this assessment, he ultimately insisted on being allowed to return to class so that he could keep learning in the few weeks he had left before the term ended and he was transferred.

After he left the office, he realized that he didn't want to return to class, and instead determined that he had to get kicked out of school in order to prevent his transfer. But as he was in the hallway pondering how to do something serious enough to accomplish this, he heard the sound of breaking glass in the science lab. When he investigated, he found Maize upset, having smashed a number of beakers and other similar glass pieces of science equipment. She initially refused to communicate the problem to him, but she finally revealed that her father had suddenly needed to leave for his work despite her belief that he would be around more and that she had been unable to even say goodbye to him. Karr then told her that he was going to be sent away, and she wondered if she could go with him, with his reply being uncertainty due to his special situation. At that moment, Namala Moffat (a teacher and the same one who had taken him to the headmaster's office the previous day) entered the room, and then left after stating that she was getting the headmaster. The two teenagers suddenly decided to leave the planet, as Maize explained that she knew how to pilot her father's shuttle thanks to him teaching her the basics. The two then locked the lab door and jumped out the room's window, escaping out onto the school grounds.

Karr and Maize made their way to her house so that she could pick up some things for the journey. On the way, she explained why her father had his own ship. Her father was a diplomat who specialized in technological systems, and in particular, interrogating captured spies and plugging holes they had exploited in First Order security. RZ-7 joined them at Maize's house with the Nuq Sin family landspeeder and they proceeded to the local spaceport where the yacht was kept. The ship took off without problems, and as they exited the planet's atmosphere, Karr lied to Maize when she asked him if he had ever been to space before, stating that he had been a few times in the past. Karr was then put on the spot when Maize asked where they were going, as she wanted to follow up on Karr's exploration of the Jedi as potential excitement for herself to participate in. Karr ultimately decided on Utapau, as it was the site of one of the last conflicts of the Clone Wars. He expressed concern about Maize's father catching them, though she stated that that was unlikely, and the conversation instead turned to Karr's family. Upon learning that his family were tailors, and that he was good at the skill, she expressed interest in someday wearing clothing he'd make, as he was a friend and his clothing was not something she could buy in a store.

Later in their journey, Sin, Maize, and RZ-7 arrived on the world of Pam'ba. It was there that Sin finally encountered his great-grandfather, Med, a former Jedi who had sought refuge on the abandoned planet to protect his family from the Empire. After sharing stories with Sin, Med passed away peacefully, having learned that his family was safe, the Jedi purge was over, and the Empire had fallen. Sin then inherited his great-grandfather's Jedi robes and lightsaber. Inspired, Sin resolved to become a Force collector, with the intention of collecting items and sharing the stories of the Jedi Order. Sin and his friends also burned his great-grandfather's home to leave no trace of the structure.

Karr Nuq Sin, being sensitive to the Force, possessed skill in the Force ability known as psychometry. This ability first manifested at the age of thirteen, causing severe headaches and seizures accompanied by distorted visions of the past whenever he touched certain objects. While he was initially unable to discern which objects would trigger such visions, through instruction from his grandmother, J'Hara, and his own exploration of the Force, Nuq Sin learned to sense which objects had a past connected to the Jedi. His visions also became clearer, and he was able to see into a great expanse of the past without suffering pain so great that he lost consciousness. One of the objects Karr has a Force vision from was a Death Star medal. Maz Kanata gave the medal to Karr to test his ability, thinking she knew the medal's history. Karr reveals to Maz that the medal belonged to Luke Skywalker. Maz tells Karr that Han Solo gave it to her to settle a bar tab and claimed that it was his medal.

Nuq Sin demonstrated talent as a tailor, the profession of his family, and eventually decided to attend trade school to further develop his skills in the craft. He also possessed the ability to build droids, combining parts from protocol, medical, and astromech droids to create RZ-7, who served as both his friend and a pseudo-medical droid. Although he was not a trained pilot, he acquired the necessary skills to adequately operate the First Order yacht Avadora from Maize Raynshi.

Karr Nuq Sin made his debut in the young-adult novel titled Force Collector, authored by Kevin Shinick. It was released in 2019 as part of the Journey to Star Wars: The Rise of Skywalker publishing initiative. The character underwent several name changes before Shinick ultimately decided on the name Karr Nuq Sin. In 2010, Shinick participated in a Dungeons & Dragons gaming session where he created the name Kai Nuq Sin for a character, which may have served as the inspiration for his Star Wars character.

Force Collector was released around the same time as the video game Star Wars Jedi: Fallen Order, a story that starred another young Force user with the power of psychometry, the Jedi Cal Kestis. According to Shinick, he wrote the first draft of the novel without knowing about Kestis' powers in the other developing project and only learned of it around a year before the book's release, in the same call that he was told certain aspects of the novel needed to be changed to avoid treading the same ground as Star Wars: Episode IX The Rise of Skywalker. What Shinick had already written was close enough to Star Wars Jedi: Fallen Order that only minor details of the rules and effects of the power needed tweaks to bring the two stories in line, such as the blinding white light Nuq Sin saw when touching an object to match what happens in the game when the player makes Kestis use his "Sense Echo" power.