Donnel Arryn was the Lord of the Eyrie and the head of House Arryn during the reign of King Daeron II Targaryen, whom he staunchly supported during the First Blackfyre Rebellion.
When Daemon I Blackfyre declared himself the true king of the Seven Kingdoms and sought to overthrow his half-brother King Daeron II, Lord Donnel called his banners in support of King Daeron and marched his army to the Redgrass Field in support. Donnel boldly lead the vanguard, which was on the verge of being overwhelmed by the Blackfyre forces until the arrival of Ser Gwayne Corbray with reinforcements.
In 208 AC, Donnel participated in a tourney at Maidenpool, where he was overthrown in the lists by Ser Humfrey Hardyng, alongside Lord Royce and Ser Donnel of Duskendale. During the Great Spring Sickness, Donnel ordered the Vale of Arryn sealed off, shutting down traffic from the high road and by sea, preventing the illness from spreading into the region.