Ysionris Jeromi

Vice Admiral Ysionris Jeromi is a living legend. He'd taken the UNSC Hopeful, a ship with no weapons or armor to speak of, into battle to save the lives of the critically wounded aboard damaged ships. He has saved tens of thousands of lives, and more than once faced a Court Martial. He has gained and lost rank over the years, but he has also won the UNSC's Colonial Cross-twice. He was a four star Admiral in 2525, and a three star Vice Admiral in 2551.

He was a personal friend to Dr. Catherine Halsey, and performed a number of experiments on Binobo chimpanzees for Dr. Halsey in 2525. He sent UNSC Priority Transmission 09872H-98 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 disapproval made her decisions more difficult. The experiments he conducted were later used on the Spartan-II soldiers. However, he was not made aware of this and likely would have objected if he had known.

In 2551, he took the Spartan-III soldiers aboard the Hopeful for Project CHRYSANTHEMUM. He was suspicious of Spartan-051, especially after a message arrived for Kurt from a secret Slipspace COM Launcher.