The Waitress worked at Café Salmonella. At some point during her employment, she encountered a man with a monobrow. She assaulted him and checked his ankle for a particular tattoo. When she did not find such a tattoo, she apologized to the man and gave him a meal free of charge. It is likely that she mistook the man for Count Olaf; her knowledge of the tattoo and its particular location suggests she is a member of the fire-fighting side of V.F.D.
She may also be the same waitress in The Penultimate Peril, who had a customer that requested sugar in their coffee, she then threw him onto the ground so she could see if he had a tattoo on his ankle, and then he received a apology and a free slice of rhubarb pie for all his trouble.