Task: Sentence Expansion
Input (English): In ABC 's " Grey 's Anatomy " , Leigh first appeared as a woman in Joe 's bar who was noticed by Derek Shepherd while in the third-season finale , it was revealed that she was Lexie Grey .
Output (English): In ABC 's medical drama " Grey 's Anatomy " , Leigh first appeared as a woman in Joe 's bar who was noticed by Derek Shepherd during the final two episodes of the third season , and her character is later revealed to be Lexie Grey , the younger half-sister of the titular character .