Claire is the shallow sister of the moody, brilliant heroine, Catherine, in David Auburn's Proof, and she could easily be played as the villain. But C. Kelly Leo brought the character to scintillating, multi-faceted life. Though you hated many of Claire's words and actions, Leo made sure you understood their source. You could tell this woman loved her crazy sister and venerated her father, but who wouldn't yearn for a conventional life after growing up with two family members who were so deeply and exclusively bonded to each other? Leo didn't downplay the character's banality, either. Her Claire masked concerns with a high-pitched voice and a smile like that of a professional airline stewardess. And she brought a terrific, controlled humor to the play. Not many actresses could bring down the house with the line "Maybe Hal would like a bagel?"