Who is Eleanor Rigby from Mortal Fear and what is their importance?

Eleanor Rigby is the online name used by EROS subscriber Eleanor Markham and Harper's online lover. She is a "moderately successful mystery writer." She tells Harper that she lives in Los Angeles with her crippled sister and seldom leaves home except to work at her second job as a body double for famous actresses. Harper will later learn that she actually doesn't work as a body double, that she has no sister but is crippled herself.