A Stick Orderly is a junior-ranking soldier assigned to accomplish minor tasks for the highest-ranking officer stationed at the location. They are generally assigned to conveying messages, carrying out summons, clearing files, and maintaining the general tidyness of the officer's desk. They may also be expected to perform mundane chores, such as fetching tea. A Stick Orderly accompanies their assigned officer whenever the latter goes on rounds.
Stick Orderlies can generally be recognized by their extra-smart and well-maintained uniform. In the Indian Armed Forces Stick Orderly for the day is chosen at the time when the ceremonial guard is inspected before they commence their duties at the Quarter Guard. Page 145 in the Indian Police Forces drill guide has a reference as to how the Stick Orderly should be selected.
Stick Orderly: For Ceremonial Guards an extra man will be deputed to allow the cleanest man being excused guard duty. The man so excused will be named 'Stick Orderly'. His duty shall be to wait on the Commandant or the senior officer in the Station, in his office to perform the duties of a 'Runner'. He will wear his Guard Mounting Uniform.
They also carry a stick orderly's baton, which generally has the ensignia of the Army unit. In the Indian Army, which has a very distinct ceremonial uniform, the stick orderly will wear the ceremonial Pagri turban and a pouch belt with a steel whistle attached to it.
References [bprd.nic.in/writereaddata/mainlinkfile/File932.pdf Indian Police Forces - Drill Manual]