The assistant manager is the smooth desk clerk of the Hotel Royale, who welcomes the Enterprise-D away team as guests and plays out the novel's plot around them.
The assistant manager appears in The Royale. He presides over the front desk of the casino hotel on Theta VIII and greets Riker, Data and Worf as a trio of expected foreign gentlemen, handing them chips on the house.
The tricorders show that he and everyone else in the building give no life signs. He is a character from a second-rate novel, recreated with the rest of its setting by aliens who mistook it for a guide to human life. He worries about the bellboy's infatuation with a woman named Rita, and about the gangster Mickey D.
At the climax the away team take the role of the investors who buy the hotel in the last chapter. Riker completes the purchase and makes the assistant manager a gift of the place, which allows them to leave.