|The title of this article is conjecture based on information revealed in the A Song of Ice and Fire novels or related material and may be subject to change.
- "Her eldest son, Jacaerys, flew to the Vale and the North, her middle son Lucerys flew to the Stormlands. Rhaenyra hoped that the war would begin and, if the gods were good, end with diplomacy. As always, they weren't."
- ―Viserys Targaryen
When Prince Jacaerys Velaryon flew to the Vale on his dragon Vermax to seek allies for his mother Rhaenyra, Jeyne upheld her house's oath to support Rhaenyra's claim to the Iron Throne. The armies of the Vale were thus sworn to her in the civil war against Rhaenyra's half-brother Aegon II Targaryen.
In the books
Lady Jeyne became Lady of the Eyrie during the late reign of King Jaehaerys I Targaryen, while still in her minority, and Lord Yorbert Royce ruled as Lord Protector, attending the Great Council of 101 AC in her stead. Jeyne would rule the Vale for near forty years and, although she was presumably a coveted match in the Seven Kingdoms, she never married. As such, she came to be known as the 'Maiden of the Vale'. When Lady Rhea Royce died, her husband Prince Daemon Targaryen appealed to Jeyne to be granted House Royce's seat of Runestone, but Jeyne rejected him and ordered him to leave the Vale.
Apart from the fact that House Arryn had already sworn to support Rhaenyra's claim, Lady Jeyne also supported Rhaenyra due to the fact that she was part Arryn herself, being the daughter of Aemma Arryn. While the snows closed the passes in the Mountains of the Moon, Jeyne sent her troops south by way of ship from Gulltown. After being driven from King's Landing, Rhaenyra was counselled to take refuge with Jeyne in the Vale by Ser Harrold Darke, but she refused this advice.
After the war, Lady Jeyne served as one of the original seven regents for Rhaenyra's son and the new king, Aegon III Targaryen. She died of an illness in Gulltown in 134 AC. Before her death, Lady Jeyne had written a will in which she appointed her fourth cousin and loyal ally, Ser Joffrey Arryn, the Knight of the Bloody Gate, as the new Lord of the Eyrie. However, the succession was rapidely contested due to the presence of closer living relatives: Ser Arnold Arryn was Lady Jeyne's first cousin, but he had tried twice to depose her by force. After his second rebellion, the Maiden of the Vale had imprisoned him in the Sky Cells of the Eyrie or the dungeons beneath the Gates of the Moon. By the time of her death, Arnold had gone insane and gained the name of the 'Mad Heir', but his son, Ser Eldric Arryn, claimed rule over the Vale by value of his close blood ties to Lady Jeyne. Many lords joined his cause, declaring that the laws of inheritance of the Vale could not be changed by the "whim of a dying woman". When a third claimant (Isembard Arryn, head of a lesser branch of House Arryn based in Gulltown) emerged in the struggle, a full-scale war of succession gripped the Vale and would even see a muddled intervention attempt by the Iron Throne, which attempted to enforce its ruling that the Maiden of the Vale's will would stand. Although Eldric Arryn was killed and the Gulltown Arryns were imprisoned, the Mad Heir fled to Runestone where Ser Corwyn Corbray, a regent for King Aegon III, was killed. Striking down the King's regent renewed the war between Ser Joffrey's supporters and those of the Mad Heir. The attempted invasion through the Mountains of the Moon failed as the royal army lost a third of its force to the hill tribes. The war ended when Alyn Velaryon, the Lord of Driftmark, and Benjicot Blackwood, Lord of Raventree Hall, forced the rebels to recognize Ser Joffrey as Lord of the Vale, allowing him to succeed his cousin as she had intended. Isembard Arryn was chosen as the realm's new Master of Coin.