Responsible for making sure that the talent knows when they are to perform, where they are to perform, and what time they are to be there. a.k.a. "Talent handler."
Handler has different meanings in many contexts- in competitive sports it means a trainer, in programming it specifies a routine that deals with a specific situation or type of data, in the CIA, FBI, etc. it means an agent's manager, and in the airport- a baggage handler... puts your bags on a little conveyor belt.
Generically, it means a person or thing which deals with a specific subdomain of interest.
A guardian responsible for escorting a retarded child or adult in public. Highly alert and well trained, these individuals can sense when their "client" is ready to change from sweet and calm to loud and destructive. Sometimes seen armed with a chair and a whip as tools for establishing control, particularly with emotional downies.