From Mystery Man on Film:
So then a funny thing happened. At the ripe young age of 68, Hitch sat down to write this screenplay himself. The protag would be called Willie Cooper. There would be two murder sequences and a big ending. The first victim, Caroline Varley, works for the United Nations, and gets offed in Central Park. Willie meets the second victim, Patti Landis, at a Manhattan art school and much suspense is drawn out of when and how Willie might murder this girl, which would eventually take place on an abandoned U.S. battleship from World War II.
And then thereâ€™s the ending. A female policewoman is sent out as a decoy to capture Willie, and he actually falls in love with her.
Hitch called it his â€œdark love story.â€ Heheheâ€¦
Now Hitch went further in the development of this film than any other project that never made it to the big screen. He was going to break new ground with the use of indoor natural lighting and a 360 degree pan of an entire apartment. He scouted locations and did test footage (the stills from those tests are peppered throughout this article). The sex and violence wouldâ€™ve broken the kind of barriers that were later broken in films like Bonnie and Clyde. Hitch was ahead of his time. Dan Auiler wrote, â€œHere is one of cinemaâ€™s greatest directors proposing a groundbreaking film that would have eschewed the American studio style for the kind of filmmaking Hitchcock was seeing in France and Italy. More importantly, [Kaleidoscope] would have returned Hitchcock to the kind of dark films that characterized his British period.â€ But Universalâ€™s rejection of his concept (and that of a serial killer protag) was absolute. It was a decision that irked Hitch to the end of his life.
The thing is, Hitch was right. His concept would have worked, and everybody was (and is) wrong about unsympathetic protags. Sympathy or its lack of has nothing to do with a great protagonist. What matters is character depth. If you have a dynamic character as your protagonist, who has many different sides to his character, a guy who is incredibly charming and yet also a demented killer, people will be repulsed and also fascinated. And if this dynamic character is surrounded by sympathetic supporting characters, they will watch the film to the end, because they will try to A) figure out what makes the killer tick, B) they will quietly sympathize with (and worry about) all of those innocent supporting characters, and C) they will root for his downfall and be overjoyed when it finally happens.