Like the rest of the Shadows in the house, Shirley is all black and appears to be a silhouette of her Face, Ram. Shirley is a young girl with curly, short hair cut in a tomboy style and wears purple Victorian style clothing with white frills and a white bow in her hair.
Due to the fact that Ram barely spends any time with her Master, we don't get to see Shirley's personality much. The best way she could be described would be as quiet and shy, like her Face.
Power & Abilities
"She can transform by wearing the soot she emits herself" - Ram (chapter 95)