Pact of Ice and Fire
At the start of the civil war, Prince Jacaerys Velaryon flew to the North to gain House Stark for the cause of his mother, Queen Rhaenyra Targaryen. Part of the alliance called for a royal princess to marry into the family of Lord Cregan Stark. Lord Roderick Dustin led the Winter Wolves to join the blacks, while House Manderly also contributed knights to Rhaenyra's side. Lord Cregan himself led a host to King's Landing near the end of the war, but they arrived after the death of King Aegon II Targaryen.
Cregan briefly governed in the capital during the Hour of the Wolf. Although a royal princess never did marry into the Starks, Cregan gained many rewards for his support of King Aegon III Targaryen.