 He was the son, perhaps the second son, of Robert de Brus, 1st Lord of Annandale.The elder de Brus' allegiances were compromised when David I invaded England in the later 1130s, and he had renounced his fealty to David before the Battle of the Standard in 1138.The younger Robert however remained loyal and took over his father's land in Scotland, whilst the English territories remained with the elder Robert and passed to the latter's elder son Adam de Brus, 2nd Lord of Skelton.