K.D. O’Hair is a rare talent — the kind of performer who inhabits a character so fully it’s almost frightening. In The Heather’s Dahlia Legault-directed production of Danny and the Deep Blue Sea, O’Hair breathed life into the role of Roberta, an emotionally wounded single mother. Sharing the stage only with co-star Vincenzo Hinckley (Danny), she beautifully captured both Roberta’s guarded exterior and buried vulnerability. From her immaculate New York accent to the way she subtly wiggled her toes, she was perfection.