Ryer Ord Star is recruited for the journey to Parkasia because Walker Boh thought it necessary to have a seer along. He wanted to bring the Addershag, but the Addershag had died years before. Ryer Ord Star was at one point the Addershag's apprentice, but her apprenticeship was cut short when the Addershag learned of her empathic abilities. Ryer's empathic skills helped make her a good healer, and her skill at healing even helped save Walker's life.
It was revealed that Ryer was actually a spy for the Ilse Witch and it was because of the witch that the seer agreed to go on the voyage on the airship Jerle Shannara. However, Ryer's loyalty to the witch faded during the journey, and she became more loyal to Walker Boh and his cause. She also found herself in a romantic relationship with the Elven Prince Ahren Elessedil. They stuck with each other throughout their journey, and Ahren used the magical the Phoenix Stone to save both their lives while they were being hunted by Antrax. With the help of the stone and Ryer's empathic skills, they also were able to rescue Walker Boh from Antrax.
When both Ryer and Ahren were captured by the Morgawr, the seer saved Ahren's life by telling the Morgawr that Ahren would become King of the Elves in the future. Although this might have been an actual vision, it was likely just quick on Ryer's part to save the man she loved.
The Morgawr used Ryer's powers to locate the crew of the Jerle Shannara, but she worked to lead the Morgawr astray with false clues and helped Ahren escape the Black Moclips, the warlock's airship. When the Morgawr found out about her treachery, he had her tortured and defiled by his crew of Mwellrets and hung her on the deck of the ship in the boiling heat until she died. At the moment of her death, the shade of Walker Boh came to her, bearing away her spirit with him into the Hadeshorn.