Fathers enemy

As Sarah walked in she looked around to try and decide who could buy her a milkshake but then suddenly she seen David he was her dad's enemy he and Frank always hated each other she didn't know why, he approached and said "Looks like you have turned into a little slut, why?" he asked puzzled.

The voice spoke "ask him to buy you a milkshake then explain everything then tell him you will do any humiliating task he asks".