Glaeruin was born in Esteldin. He was named by his dying mother, for it was influenced by his father as well since he was fighting a grievous battle against orcs in their own encampment. His mother died by childbirth, and his father returned to Esteldin to see his only son and his dead wife. Glaeruin's father felt grief and sorrow, yet seeing his son he felt relieved and happiness. As soon as Glaeruin could walk and hold a sword, as tiny as it was, he was taught in swordsmanship, tracking, herb-lore and such. Glaeruin trained with his father when it came to Swordsmanship, and his Aunt in Herb-lore. He sparred with the other children his age, being one of the swift and strong ones among them. Everyday and hour of said day, did he train hard, with few breaks if needed.

When Glaeruin was the age of sixteen, he and his father set out into the Wilderness to hunt. It was deemed that Glaeruin was ready then, and so his father put him to the test with hunting Wargs that had settled near Esteldin, although Glaeruin was fearful first he did pull in when he had to for he was sent off several times to gather herbs and butcher rabbits and the like. It was the final day of their hunting trip, they had killed most of the Wargs near for they were few, yet one whose came to kill them in revenge was the alpha which had escaped beforehand. The Alpha slowly crept upon them, piercing yellow eyes were among the trees, but yet as it's black highlighted hide hid in the night, it made no noise and left silence. It was then when the Warg pounced on Glaeruin, his two paws latched onto his shoulders and left them with shreds, whereas his jagged teeth bite his stomach but the Warg yelped as a sword severed his upper torso from his bottom, Glaeruin had reached through the pain and grabbed his blade, thus ending the Warg. After they had recovered, they returned to Esteldin, where Glaeruin started to study Wargs and their behavior, trying to learn as much as he could so that he may know their weaknesses. He had learnt all he could from books mentioning Wargs, and from his encounter with the alpha, he knew great knowledge about them.

Twenty-four years later, Glaeruin decided to go down to the Lone-lands as it was in peril of the Wargs, Half-orcs, and more threats of the Free Peoples, and still to this day does he protect it.