Mrs. Cheveley's unwelcome arrival upsets the happy stasis of our hero's life. She comes with a purpose: to make money. What about the demise of Sir Robert's career and the demolition of his marriage? Amusing byproducts. We believe Mrs. Cheveley when in Act III she denies that her motive is spite. But she's accustomed to trampling a few people in her pursuit of fame and fortune. Mrs. Cheveley is a resourceful and tireless villain. Just consider that moment at the end of Act 3. She's got the diamond handcuff on, and she's given up the letter. All seems lost. But Mrs. Cheveley never says die. She says: "please get me a glass of water" (3.292). And she steals the pink letter she thinks is a love note, further plotting against Lady Chiltern. Hmmm, maybe there's a little dash o' spite mixed in her motives, after all.