Orthallen was Lord of Wyvern Reach, uncle to Herald Kris, and a close personal friend of King Sendar and Queen Selenay of Valdemar. He befriended Sendar before he was even Chosen by his Companion, and the two became best friends. By the time Selenay became Queen, he was the most senior member of the Council. However, Orthallen had loftier goals than that of senior councilor: he wanted to be King. To that end, Orthallen began plotting his takeover from a young age.
Once Selenay became queen, he fed her dreams of romance, and served as a sponsor to Prince Karathanelan. Once Selenay and the prince were married and Elspeth was born, he helped Karathanelan try to assassinate her. This plot failed.
Later, he promised Ancar of Hardorn that he would deliver Selenay and Elspeth to him if he could be King of Valdemar. Orthallen is also the suspected sponsor of Elspeth's nurse Hulda and the mastermind of several illicit industries in Valdemar, including the slave trade. In addition, it is possible that he had a role in the death of Talamir and the attempted murder of Talia by "Blues" (unaffiliated students) while she was a trainee.
Although Orthallen was careful to keep up his facade as a benevolent person who only wanted the best for Valdemar, Companions didn't like him. Alberich and Kantor didn't trust him from the beginning, though they had no proof to back up their dislike. It was Alberich who warned Talia and Elspeth to be suspicious of Orthallen's intentions.
When Talia arrived in Haven, after assuming some of the duties of Queen's Own she noted that Orthallen didn't like her overmuch, and she felt uncomfortable around him. After her internship, where rumors of her instability almost became true, she didn't trust him and this led to fights with her mentor, Herald Kris.
Eventually Talia brought back proof of Orthallen's treachery. Realizing he was trapped, he tried to kill Talia. Instead, Elspeth killed him with throwing knives gifted to her by Skif.