Ysionris Jeromi

Admiral Ysionris Jeromi was the Chief medical officer of the UNSC Research station Hopeful in 2525.

He was a personal friend to Dr. Catherine Halsey, and performed a number of expirements on Binobo chimpanzees for Dr. Halsey. She was his star pupil, and he had never approved of her working with the Office of Naval Intelligence. He was a mentor to her and his dissaproval made her decisions more difficult. The experiments he conducted were later used on the Spartan soldiers. However, he was not made aware of this and likely would have objected if he had known.