In Straken it is mentioned that Queen Arling Elessedil would likely be succeeded by the daughter she had with King Kellen Elessedil, as Kellen and his sons Kiris and Wencling were killed by the Federation. However, in Wards of Faerie a retroactive continuity is established where Arling is said to have been succeeded by a son named Emperowen. Emperowen also had a brother named Ellich Elessedil, which means that Arling had two more Elessedil sons besides Kiris and Wencling.
Presumably this retroactive continuity means that Emperowen and Ellich were sons of Kellen as well as Arling, as they would not have had Elessedil blood otherwise.
Quest for the Missing Elfstones
By the time his granddaughters Aphenglow and Arlingfant were young adults, Emperowen had been King for nearly eighty years. Age had caught up with him, and he struggled with chronic heart and lung problems. He was also demoralized by the impending transfer of power to his son, Phaedon Elessedil, because he no longer saw it as a good idea.
When Aphenglow, a member of the Druid Order, discovered that there may be a way to find the lost sets of Elfstones, the Ard Rhys Khyber Elessedil decided to undertake a quest to find them. Aphenglow came to Emperowen to ask his permission to use the Seeking Stones in order to determine the other Elfstones' whereabouts. Because of the objections of Phaedon and of other members of the Elven High Council, Emperowen did not loan the Elfstones to Aphen and instead compromised by allowing her to use them only within the confines of Arborlon.
Quest to Restore the Forbidding
Later, when his granddaughters informed him that the current Ellcrys was dying and that Arlingfant had been chosen to become the new Ellcrys, Emperowen gave the Elfstones to the sisters without telling Phaedon or the High Council, so that they could find Safehold and the Bloodfire.
Some time after the sisters embarked on their quest, Emperowen and Ellich informed the Druid Seersha that Tael Riverine and his Demons had broken free of the Forbidding and were moving to attack the Federation stronghold of Arishaig. They asked Seersha to convince the Elven High Council of the need for the Elves to ally themselves with their historic enemy, and she was successful: The High Council voted seven to two to ally with the Federation, with Phaedon being one of the dissenters.
Emperowen was killed in his sleep by a Changeling-type creature under the command of the Federation Prime Minister, the sorceress Edinja Orle. The creature framed Ellich for the murder, and Phaedon, who succeeded his father as King, used the opportunity to throw Ellich in jail and to try and imprison Seersha in retaliation for her success in getting the Elves to ally with the Federation. Seersha was warned of Phaedon's plan by Sian Aresh, Captain of the Home Guard, and she fled Arborlon with Crace Coram, intending to find Aphenglow and Arlingfant and to warn them to stay clear of Phaedon.
Ultimately however, Ellich was the one who succeeded Emperowen: Phaedon had a mental breakdown after witnessing Edinja Orle's creature kill Sian Aresh and another member of the Home Guard before it was stopped and killed by Seersha. Phaedon's incapacitation and the realization that the creature had killed Emperowen led to Ellich's exoneration and his crowning as King of the Elves.
Ultimately, Emperowen's reign signaled the beginning of the end of centuries of Elessedil rule. With Phaedon incapacitated, Afrengill withdrawn and uninterested in political life, Aphenglow occupied as Ard Rhys of the Druids, and Arlingfant become the Ellcrys, there was no one in the family left to take over when Ellich passed away. The crown went to a member of the Ostrian family who became Queen of the Elves.