House Costayne is a noble house from Three Towers in the Reach, sworn to the Hightowers. Their seat Three Towers is located on the southern coast of the Whispering Sound, they blazon their shield with quartered: a silver chalice on black, a black rose on gold. Lady Elinor Costayne was a member of House Costayne and one of the many brides of King Maegor I Targaryen. Before marring King Maegor the Cruel, Elinor was married to Ser Theo Bolling and had already given her husband three children, however Theo was arrested by knights of the Kingsguard, accused of conspiring with Queen Alyssa Velaryon to place her son, Prince Jaehaerys, on the throne, and was executed. After seven days of mourning, Elinor was summoned to wed Maegor against her will, one of many women forced to do so. She became pregnant and gave birth to a stillborn abomination said to have been born eyeless and with small wings, she was one of three women forced to marry Maegor at this time the other two were Jeyne Westerling I and Rhaena Targaryen . She was one of the two wives who survived the king.
Later during the Blackfyre Rebellion House Costayne sided with the Blackfyers, and fought at the battle of the Redgrass Field, and later attended Lord Ambrose Butterwell's wedding festivities which was a secret attempt to place a Blackfyre on the Iron Throne.
