Like Algernon and Jack, she is a fantasist. She has invented her romance with Ernest and elaborated it with as much artistry and enthusiasm as the men have their spurious obligations and secret identities. Though she does not have an alter-ego as vivid or developed as Bunbury or Ernest, her claim that she and Algernon/Ernest are already engaged is rooted in the fantasy world she’s created around Ernest.
Cecily is probably the most realistically drawn character in the play, and she is the only character who does not speak in epigrams. Her charm lies in her idiosyncratic cast of mind and her imaginative capacity, qualities that derive from Wilde’s notion of life as a work of art. These elements of her personality make her a perfect mate for Algernon.