Complex sentence: In every version of the story in which she appears, Mrs. Lovett is the business partner and accomplice of barber/serial killer Sweeney Todd; in some versions, she is also his lover.
Split into simpler sentences: In every version of the story in which she appears, Mrs. Lovett is the business partner and accomplice of barber/serial killer, Sweeney Todd. In some versions of the story, she is also his lover.