"Percy and the Shrinking Violet" is an Oz short story by Rachel Cosgrove Payes, published in Oz-story Magazine No. 1 in 1995. As the title shows, the author returns to one of her favorite characters, Percy the giant white rat.
Violetta, statuesque and raven haired, is a "mighty sorceress" and an ambitious woman. Though she rules her own little island in the middle of Lake Lavendra in the Gillikin Country, she covets more power — specifically, the power of Princess Ozma. Through a child minion, she sends Ozma a pot of enchanted shrinking violets. (The boy is called "Bloo, Crim's son" — crimson + blue = purple, the Gillikin color.) The scent of the violets will cause anyone who smells it to shrink to one foot tall.
Ozma, however, is absent; Percy intercepts the present, much to Bloo's distress. Soon, both Percy and Jellia Jamb are feeling the effects; but they do not guess the cause until Ozma is also affected. Using the Magic Picture, they begin to penetrate the mystery. Percy convinces Ozma to send him to Violetta's island with her Magic Belt to do what he can. Though Percy is normally proud and possessive of his giant size, it is ironically his return to smaller stature that allows him to resolve their problem.
Soon, Ozma, Jellia, and Percy are back to normal, and Violetta is stripped of her magic. The good order of Oz is restored.