When Glurg was a child, his entire goblin tribe (called Harglahr, loosely translating to "Knucklebones”) was captured by slavers and taken to Skullport, where a Red Wizard named Volchuul purchased him as a cupbearer/test subject. Volchuul made Glurg ingest a multitude of vile concoctions, and through some miracle of biology or good fortune, the young goblin never died. Impressed by his slave's apparently impervious constitution, Volchuul allowed Glurg to be his apprentice, confident that the goblin's fear of him would stay his hand if he ever sought to raise it against his master. He taught the goblin to read, how to focus his will, how to pick at and pull the threads of the Weave, boasting to his colleagues of the “tricks I’ve taught my little pet!” For a while, Volchuul was indeed safe. Glurg was an attentive student who treated his master's cruelty and caprices as crucial lessons in his study of spellcraft, and he suffered without complaint or recalcitrance. But Volchuul’s assumption that Glurg's fear of him was greater than his aspirations of betrayal proved to be dead wrong. After a night of heavy feasting, Volchuul lay down in his chamber, drowsy with wine, food, and a tasteless poison for which Glurg had long since developed a tolerance. Volchuul’s blissful slumber curdled into discomfort, followed by terrified agony. As the wizard convulsed and sputtered his last breaths, Glurg picked up the wizard's spellbook, climbed into a comfortable chair, and began reading.

The tale of Yolchul's demise reached Xanathar's majordomo, Ahmaergo, two days later, and the dwarf sought out Glurg at once, promising the goblin wizard influence and wealth beyond his dreams if he would lend his skills to the Xanathar Guild's nefarious schemes. Glurg knew better than to trust the Xanathar Guild, but he craved the freedom and opportunities for cruelty that the criminal empire offered.