Byzantine officials would generally have a retinue or retainers that followed them and would act as a personal body guard along with just being general assistants. In the sources this is often referred to as "groomsman," and things of that nature, but it meant you were a follower of a certain person. For example, Basil I came to power by working in the retinue of Emperor Michael III and becoming such a close associate that he was able to assassinate them. They overtime would become incredibly powerful, especially those of the Emperor and his senior officers whose retainers were referred to as the Bucellarius, and eventually they would become the Tagmata, or the elite infantry that formed the core of the now expansive Byzantine Army in the 9th century.