At some point early in his life, Ebrose committed himself to the life of a maester, and would have studied at the Citadel in order to forge his chain of service. Eventually he rose through the ranks, ultimately achieving the position of Archmaester, making him one of the most senior members of the order.
Samwell Tarly assists Ebrose with the dissection of the body of Maester Wayland, weighing the organs in a scale. Samwell repeats his request to access the restricted section of the Citadel's library in order to research the White Walkers, a request which Ebrose denies. While Ebrose assures Samwell that he does believe his claims regarding the Walkers, he explains the reason for his reluctance, and emphasizes that the duty of a maester is to be skeptical.Ebrose examines Jorah Mormont's Greyscale, and deems it too advanced to treat. Even when asked by Sam if he can try, he still remains adamant that Jorah's condition is his end. He states that he would normally send Jorah to Valyria to live with the Stone Men but, with Jorah being an annointed night, he will allow him one more night at the Citadel in which Jorah can take his own life.
Despite Ebrose explicitly forbidding him form treating Ser Jorah, Sam does so anyways and is able to cure him. When Ebrose arrives in the morning to see to Jorah, he finds him completely healed. Despite being told by Jorah that no one tended to him, Ebrose realizes immediately what Sam has done and calls him into his office. There, he congratulates Sam on saving Jorah's life with a procedure few Maesters have ever mastered. He then immediately orders Sam, who had expected a reward, to copy some old scrolls - telling him that his reward is not being banished from the Citadel for ignoring orders.
Later, Ebrose and the other Maesters discuss Bran Stark's letter warning that the army of the dead and the White Walkers are marching south towards Eastwatch-by-the-Sea. He and the other Maesters are skeptical of this report and dismiss Samwell Tarly's efforts to vouch for Bran. Ebrose himself opines that the letter could be disinformation spread by the self-proclaimed Queen Daenerys Targaryen. They agree to investigate these claims further and to send a letter to Winterfell inquiring into Bran's claims. When Samwell leaves the room, the other Archmaesters discuss the death of his father and brother, however, Ebrose announces that he had not had the heart to tell Sam of their fate.
Archmaester Ebrose is a member of the order of Maesters in service at the Citadel in Oldtown. His ring, mask and rod are made of silver, signifying that he specializes in the arts of healing.