When Kuinn's father, Muninn, arrived with his young family in the cold and harsh Grey Mountains three years prior to Kuinn's birth, they were met with a frosty reception from the local Longbeards. The hardened miners and some of the guards openly disputed King Thráin's decision to appoint "an exile" as the First Lord of Thakalgund. The locals branded anyone who wasn't born in one of the four Longbeard halls as "exiles," and this prejudice made it clear to Muninn that he had to prove himself as the new Lord of Thakalgund.

The Hall of Thakalgund had experienced an influx of exiles from the Lonely Mountain ever since Smaug's attack almost 40 years ago. Only a handful of dwarves from the Lonely Mountain chose to stay in the unwelcoming Grey Mountains, drawn by the promise of untapped riches in the form of gold, silver, precious gems, and iron. The Halls of the Grey Mountains had fallen into disrepair after the Great War of Orcs and Dwarves, with many of them attacked by Orcs. The surviving miners and guards either perished in the battle or chose to join the Royal line in the Blue Mountains.

Undeterred by the skepticism and adversity, Muninn, with his wife Ásdís, who was pregnant at the time, and their seven-year-old son, Duinn, set out to rebuild the ruined Halls of Thakalgund. Muninn worked tirelessly alongside the builders and engineers he appointed, earning the respect of the hardened locals. By the time Kuinn was born in 2811, much of the main Hall had been rebuilt, including the Hall of the First Lord. The celebration of Kuinn's birth in the Hall of Thakalgund marked a turning point in the acceptance and unity of the Grey Mountain dwarves.

As Kuinn and his older brother, Duinn, grew up, the dwarven population of the Hall slowly increased. Rumors of the rebuilt Thakalgund Hall and its abundant mines attracted dwarves from the West, South, and East. Ásdís, being the daughter of a Lord, ensured that her sons received the best education, summoning wise elder masters of Lore from the Blue Mountains and the Iron Hills. Muninn also called upon his old shield brothers to join him in Thakalgund, forming a strong military guard to protect the Hall from frequent Orc attacks. Kuinn and Duinn were trained in various weapons and combat techniques by seasoned warriors who had survived the Battle of Azanulbizar. Kuinn developed a particular affinity for the axe, war-mattock, and hammer, while his older brother excelled with the sword and bow.

Unlike his parents, who arrived in the Grey Mountains later in life, Kuinn was born there and spoke with a distinct Grey Mountain accent. The icy winds and perilous landscapes became an integral part of his daily life. As Thundercleft, the mountain under which Thakalgund was built, overlooked the Orc-infested Gundabad in the East, the dwarves of Thakalgund were constantly reminded of their holy lost hall.

The veteran warriors who trained the young Kuinn soon realized his unparalleled lust for battle. While many of the young dwarves in training were eager to fight Orcs, Kuinn's desire to prove himself in battle surpassed that of his peers. At the age of 17, Kuinn, driven by his impulsive nature, set out on a solo expedition towards Gundabad, seeking to spill Orc blood for the first time. Unbeknownst to his family and the Thakalgund community, he took his pack and training axe, venturing into the dangerous territory.

When night fell, Kuinn made camp deep within the shadows of the mountains. In the eerie silence of the frozen night, he heard distant growls and clattering armor. Sensing an imminent attack, he prepared his weapon, ready to face his first real combat. The sounds grew closer, and soon enough, a pack of vicious Orcs emerged from the darkness, their eyes gleaming with malice.

With adrenaline pumping through his veins, Kuinn fought valiantly against the Orcs, his training guiding his every move. He skillfully wielded his axe, dispatching his enemies with precision and determination. The battle lasted for what felt like an eternity, but eventually, Kuinn stood victorious, his axe stained with Orc blood. The young dwarf's triumph echoed through the mountains, a testament to his bravery and skill.

Despite the awe-inspiring display of Kuinn's skill and strength, his father Muninn was far from amused by his reckless behavior. Concerned that Kuinn's actions could endanger the entire Hall, Muninn scolded the young dwarf sternly, determined to set an example for all the young dwarves in Thakalgund. Harshly punishing his son, Muninn sent Kuinn to "Ubzur-ubraz" ("Deep Gold" in the common tongue), the deepest and most challenging gold mine in Thakalgund.

While Duinn completed his military training, Kuinn toiled in the mines from dawn till dusk. Despite Ásdís's pleas to have her son by her side, Muninn insisted that Kuinn learn his lesson the hard way. Muninn declared that Kuinn would work the mine for ten years and remain within the halls of Thakalgund until the age of 75, considered the appropriate age for travel readiness.

Resolute and without complaint, Kuinn accepted his father's judgment and labored in the mines. Through the years, he became as strong and resilient as the very rock he extracted. The power in his arms surpassed that of dwarves many times his age. When Kuinn reached the age of 27, he was allowed to leave the mine. Surprising many, he made an unexpected request to his father: to remain in Ubzur-ubraz and be given leadership over the mine. It was unusual for a dwarf of his age to hold such a position, but Muninn granted Kuinn's wish.

Thus, at a remarkably young age, Kuinn displayed his exceptional leadership skills and earned the respect of his fellow miners. Over time, his reputation as a fair and determined mine-boss grew throughout the depths of Ubzur-ubraz. Kuinn's interest in mining eventually led him to explore the field of engineering, where he showed great promise. In 2881, at the age of 70, Kuinn achieved a significant milestone as he was accepted into the prestigious "Brotherhood of Stone," becoming the youngest member ever to be welcomed into the renowned guild of engineers.

Meanwhile, as Duinn had departed from Thakalgund years earlier, Muninn appointed Kuinn as the Second Lord of Thakalgund, serving as Muninn's adjutant and designated successor to the Lordship. Kuinn's exceptional engineering skills reshaped many halls, spans, and fortifications throughout the Grey Mountains, leaving a lasting imprint on the region. News of his talent reached the King in the Blue Mountains, leaving Muninn with no choice but to allow his youngest son to travel before the customary age of 75. King Thorin himself requested Kuinn's engineering expertise for a new mining project in the Iron Hills.

Setting off for the Iron Hills, Kuinn assumed the leadership role in rebuilding the outer wall of Barukkhizdîn, which had recently suffered an attack and been left in ruins by Orcs from the East. It was in Barukkhizdîn that Kuinn first encountered Mirdrid, a young dwarf whose father was a Blacklock miner who had arrived in the Iron Hills fifty years prior. Though Mirdrid's mother hailed from the Longbeard lineage of the Iron Hills, her black beard and hair left no doubt about her Blacklock heritage. The love between Kuinn and Mirdrid grew strong, and it became evident to all that Kuinn had no intention of waiting until the customary ninetyeth year to marry his beloved. At Muninn's request, however, the couple agreed to wait a few more years. Finally, in 2896, the time for their wedding arrived. Muninn insisted it take place in the Grand Hall of Thakalgund.

As the company traveled the snowy paths, relentlessly in day and night, taking little restbit, Kuinn was ever at the side of his Mirdrid, fearing for her safety out in the open.  His fears were proven just, when at midnight, only a day's march to the East of Thakalgund the company was attacked by a group of Trolls.  Kuinn saw his Midrid in danger and charged the Trolls.  Many of the company were crushed by the powerfull Trolls, reducing the size of the Guard to a handful of dwarves.  Though the company managed to take down two of the trolls, the biggest of them was still on his feet and had set his eyes on Mirdrid.  When the troll tried to grab her, Kuinn jumped forward and swung his hammer at the troll.   Alas Kuinn missed the troll, who was quicker on his feet than most trolls.  When the smelly troll grabbed Mirdrid by the legs and lifted her up above his mouth, as if to eat her right there and then, Kuinn felt a firey rage engulf him. He balled his fist and jumped at the head of the troll, hitting him hard on the chin.  To the amasement of the rest of the company the troll looked slowly at Kuinn, as if unsure at what had happened.  Slowly the troll, who now seemed rooted to the ground, opened his hand, letting Mirdrid fall to the ground. While doing so his eyes rolled to the back of his head and he fell backward crushing the ground below him.   Kuinn had slain the troll with one blow of his fist, had saved his maiden and many other dwarrows of the company. When arriving the next day at Thakalgund the tale of Kuinn "Stonefist" was heared by all. 

In 2896, Kuinn Stonefist, son of Muninn, wed Mirdrid, daughter of Dridin. During Kuinn's fifteen-year absence in the Iron Hills, significant changes took place in Thakalgund. Imbrin Shadowbeard, a renowned and influential rune-keeper, had seen his power and influence steadily grow. Imbrin made no secret of his disdain for Lord Muninn and his sons, believing himself to be the rightful Lord of Thakalgund and its mines. Despite the majority of dwarves embracing their new Lord and moving past the dark times of Coalbrow the Tyrant, Imbrin still commanded a faction of support.

Imbrin seized the opportunity to bolster his influence when Kuinn departed for the Iron Hills. Rumors began to circulate in the halls of Thakalgund, suggesting that the gold caravans destined for the Blue Mountains never reached their intended destination and that Lord Muninn was hoarding the wealth for himself. Other rumors claimed that Muninn planned to exploit the mines until they ran dry and then abandon Thakalgund with all its riches. Despite Lord Muninn's best efforts, Imbrin's grip on the dwarves of Thakalgund grew stronger with each passing day. Muninn's advisor, Albitúr, spoke of dark magic and advised his lord to eliminate Imbrin before the entire hall turned against them.

By 2901, Imbrin's power had become so formidable that many miners refused to deliver their daily hauls to the vault, accusing Lord Muninn of thievery. Upon learning of this defiance, Muninn decreed that Imbrin be exiled from the Grey Mountains. However, despite his banishment, Imbrin's threat to the halls remained. That same winter, Kuinn's wife, Mirdrid, experienced a difficult and painful childbirth. It became evident to Albitúr, Muninn's advisor, that Imbrin's dark magic was at play. With the assistance of a lore master from Rivendell, Mirdrid and her son, Kandral, were saved. Muninn declared Imbrin and his followers outlaws, placing a bounty on their heads.

For the next thirty years, Imbrin and his followers eluded the Thakalgund guards, while Imbrin's power continued to grow within the halls. In 2906, Kuinn and Mirdrid welcomed their daughter, Una, who became Kandral's younger sister. Recognizing the threat that Imbrin posed to his home and young family, Kuinn made the decision to lead the Thakalgund guard in hunting down Imbrin. However, Imbrin continuously evaded capture through his cunning and dark magic.

When Muninn chose to remain at Erebor after the Battle of Five Armies and entrusted his title to Kuinn, Imbrin saw an opportunity to reclaim Thakalgund. Imbrin amassed a formidable force that dwarfed the Thakalgund guard. Although many valiantly fought against Imbrin's followers as they charged the gates of Thakalgund, it became clear that the young Lord of Thakalgund had to flee if his family's line was to survive. Kuinn ordered his son and daughter to escape the hall to ensure their safety. Thus, young Kandral, accompanied by Goimi Silverbeard, Kuinn's trusted right-hand, fled to the Shire, while Una, Mirdrid, and Kuinn sought refuge in the Lonely Mountain. It was there that Kuinn, along with his father and brother Duinn, devised a plan to reclaim their ancestral halls.

In the year that followed, Kuinn led a host of dwarves from the Lonely Mountain and successfully reclaimed Thakalgund, ultimately slaying Imbrin in the process. Unfortunately, due to the chaos of the battle, Kuinn believed his son to have perished at the hands of Imbrin, just as Kandral believed his father to have met the same fate. Unbeknownst to each other, their family survived the attack and successfully reclaimed the halls. It wasn't until over forty years later that, through a stroke of luck, the family was joyously reunited.

Now firmly established as the Lord of Thakalgund, with the support of his subjects and the King of the Lonely Mountain, Kuinn eradicated the memory of Shadowbeard and his followers. He ruled with confidence and prosperity, ensuring the prosperity and well-being of his people for years to come.