Thrall is the son of Durotan, former chieftain of the Frostwolf clan, and Draka. As a baby, he was found amongst the bloody bodies of his murdered parents by Aedelas Blackmoore, commander of the internment camps which held orcs after the end of the Second War. Blackmoore gave him the name Thrall, which was another word for "slave" in the human tongue. Blackmoore returned to his fortress, Durnholde Keep, with Thrall, and raised him as a gladiator — with all the savagery of an orc, but with the keen strategic intellect of a human. He was trained and taught by many, wet-nursed by a human woman, and grew to befriend her daughter, Taretha Foxton. Thrall proved to be an excellent student and a phenomenal fighter.
He was clever, quick and enormous even by orc standards. However Blackmoore's abusive beatings both in and out of the ring began to take its toll. Taretha began to write him letters and secretly delivered them to him in his cage within books, and he wrote back to her. Eventually, he wrote to Taretha that he wished to escape.
Taretha created a diversion inside Durnholde Keep which allowed Thrall to escape from his cell unnoticed. They met up outside the fortress by a cave, and Taretha gave him provisions and supplies. He then left Durnholde, hoping to never return.
However, Thrall was captured and taken to an internment camp run by one Lorin Remka. It was here that he met an old orc with glowing red eyes named Kelgar, who told him of the corruption of Gul'dan, and how the old ways had been so much better for the Horde. He told him that the only one still thinking of embracing this was the undefeated Grom Hellscream, Chieftain of the Warsong clan. When another orc told Thrall that Blackmoore had arrived at the camp looking for him, Thrall escaped again, and sought out Grom Hellscream.