He was discovered by a man named Thengir, King of the Russ, who had organized a party of hunters to clear the wolf pack from his lands. As most of the wolves were slaughtered the young man was captured and brought to Thengir who took him into his care, under the name of Leman Russ.

The Primarch learned the ways of man quickly, and many legends sprung up about him. Upon his adopted father's death, the leadership of the Russ passed to Leman. Leman became a mighty leader, winning many victories, often fighting alongside packs of Fenrisian Wolves, led by two of his Wolf-brothers who escaped Thengir's hunters.