Natural son of Lord Roose Bolton, got upon a miller's wife under a tree at the side of a stream while her husband swung from its branches. Roose acknowledged the boy enough to send him a yearly allotment of grain and a man called Reek to attend him, and otherwise let him grow up half-wild on the smallholding his mother kept. He came into his father's notice only after his trueborn half-brother Domeric rode out to meet him and died of a bad belly within the week.
Took the Hornwood lands by abducting the widowed Lady Donella, marrying her at swordpoint, and locking her in a tower to starve until she chewed her own fingers off. Was sent in pursuit of the escaped Theon Greyjoy and rode back from the sack of Winterfell with the burned ruin of a man he called Reek and a story no one in the North quite believed. Legitimized as a Bolton in 299 AC by royal decree of King Tommen, at the request of his father the new Warden of the North.