In Goidelic mythology, and especially in Scotland, Brian was a pompous man who helped Cailleach rescue Deò-ghrèine. He was a son of Tuireann, and brother to Iuchar and Iucharba (these have many variant spellings).
In Irish mythology, the sons of Tuireann and Danand murdered Cian, the father of Lugh, one of the greatest of the Tuatha Dé Danann. They also dismembered his body and tried to cover up their crime. In recompense, Lugh made them quest all around the known world as far as Persia fetching magical weapons, which Lugh planned to use at the Second Battle of Magh Tuiredh. They succeeded in obtaining all that Lugh demanded, but returned to Ireland desperately injured, pleading for Lugh to heal them; but the latter refused.
In at least one version of this tale, Brian is actually the clever and subtle one, while his brothers Iuchar and Iucharba are bumbling and easily overawed by Brian. This tale of the Sons of Tuireann has sometimes been likened to an Irish Argonautica.[1]