Durlin is of the Durin’s Folk that live in the Blue Mountains south of the Grey Havens. After the attack on Erebor, the Lonely Mountain, Durlin’s grandfather, escapes with Thrór, Thráin II, and Thorin II. They endure great hardships together but they manage to settle in the southern portion of the Blue Mountains. There he had a single son, who was Durlin’s father. Durlin grew up in the mines of the Blue Mountains and was content.

Durlin was forced to watch the exile of his elder brother, Grómli, when he was 24 years old. He tried to convince him to let him come with him, fearing what the wild would do to a lone dwarf wandering in the open, but Grómli wouldn’t have it. Durlin was much too young to join in on Thorin’s journey, so he remained in the Blue Mountains, even after the dwarves reclaimed Erebor. He seemed to enjoy the mines in the west, always hoping that his brother would be forgiven and return. But the dwarves never forgot Grómli’s treachery, and never spoke of allowing him to return to their kingdom.

Durlin spent most of the long years in solitude and mining for riches in the Blue Mountains. They may not have had the mithril of Moria, but they had their own sources of gold and jewels in the depths of the mountains. He excelled the most at the craft of weapons. He made a large, single-headed axe for himself and a double-headed axe for Grómli, which he planned to give to him upon his return.

Eventually, Durlin became more and more restless in his life and desired to know what had happened to his elder brother. He took his trusted pony, Nar, and went out in search for him. He spent six months searching for him, until he found him in Rivendell in the winter of 3018. Grómli showed no desire to return to the mines, and Durlin decided to stay in Rivendell with his brother by the grace of Lord Elrond.