Mrs. Fainall has some important functions in the play. She is the mainspring in Fainall's counterplot; when she is made aware of Mirabell's plot, she talks too freely with Foible and is overheard. She helps fill out the gallery of portraits: How would one see the world properly without a woman who was one of the conquests of the hero before he found his true love? The cast mistress, now a sadder but wiser person, is, in fact, a common character in Restoration comedy. (The curious may look at Etherege's famous play, The Man of Mode.) She is not as well drawn as the other characters, and it is perhaps easier to see why Mirabell tired of her than why he ever loved her in the first place.