The Pact of Ice and Fire was a military and political agreement between House Stark and House Targaryen agreed during the early stages of the Dance of the Dragons.
History[]
Shortly after the death of King Viserys I Targaryen, Prince Jacaerys Velaryon flew his dragon, Vermax, to Winterfell to try and secure the support of Lord Cregan Stark for his mother, Rhaenyra Targaryen, during the ensuing civil war. It was agreed that, in exchange for Stark support of Rhaenyra, the firstborn daughter of Jacaerys would marry Rickon Stark, Cregan's young son.
According to Mushroom, whilst at Winterfell Prince Jacaerys fell in love with Sara Snow, Cregan's bastard half-sister, and promptly bedded her. Cregan was initially furious, but Sara insisted that she had wedded Jacaerys first. This may have contributed to the Pact, though Archmaester Gyldayn refutes the talk of marriage, and even suggests that Sara was a fictional construct also.
Lord Roderick Dustin led the first set of Stark troops that marched south, with Cregan following at the head of a second force. Prince Jacaerys would never father a daughter to marry Rickon, as he was killed during the Battle of the Gullet.
Instead, Cregan served as a loyalist to King Aegon III Targaryen, arriving in King's Landing after the poisoning of King Aegon II Targaryen. He briefly served as Hand of the King, dispensing justice on the people who poisoned the previous king. Ultimately, a Targaryen princess never did marry into House Stark, though Cregan's loyalty was well rewarded by Aegon III, with many rewards bestowed upon him.