Answer:
All of the women the narrator wishes she could be
Step-by-step explanation:
The lady behind the backdrop speaks to the storyteller's curbed self that she imagines as a detainee in the local circle of her life.
This lady is the appearance of the storyteller's constraint, her accommodation to the enchantment of madness spoken to by the yellow shade of the backdrop. As the storyteller discovers "things in that paper that nobody knows but me, or ever will," she perceives the faint figure of a woman "shake the pattern, just as if she wanted to get out." Eventually, the storyteller moves toward becoming focused upon the example of the backdrop that changes with the light in the room and the assume that has all the earmarks of being caught behind the pattern.