The Threepenny Opera and Sweeney Todd had a night of hot, uninhibited action. Things took their course, and soon, they had a child they couldn't take care of on their hands. Fortunately, The Rocky Horror Show and Jesus Christ Superstar had always wanted a child of their own but had been unable to conceive, and they were happy to take the new baby off of the unfortunate couple's hands. Occasionally, Trent Reznor and The Phantom of the Opera would come over and babysit.
That child, ladies and gentlemen, grew up to be Repo! The Genetic Opera.