Jimmy, now the Co-Emperor of the Dinos with Ronald, has for a long time been one of the key men in the empire yet often has been away from the headlines. Jimmy rose quickly through the ranks of the army, being a skilled, brave and intelligent soldier. By the time of the dying days of Juliawaki's regime he was commander of the 6th Legion.
When Juliawaki's weakness allowed SS Commander Telavason to seize power and he had Ronald arrested Jimmy immediately saw that things had to change. He led his 6th Legion to a titanic battle with the SS which left his legion reduced to a few hundred survivors. After Ronald took over Jimmy was promoted to Senator and became the Minister of the Interior (the 6th Legion became the vanguard of the Emperor and remained at 200 strong).
Thus Jimmy basically ran the empire while Ronald and G-B-H had adventures across the galaxy, his role was largely unseen but vital. When Ronald took his extended leave from the empire (in which he created the DDS) he left the empire in Jimmy's hands, knowing it to be safe.
When M-B-H was overthrown Jimmy was the ideal choice to become Co-Emperor, indeed many said that Jimmy had been defacto Co-Emperor for decades. Strangely though since his election Jimmy has become much higher profile, differing with Ronald on his vision for the future of the empire. Jimmy however remains one of Ronald's closest allies and friends.