The Nilo/Francisco Rabal Hitman Character - who was he sent to kill? (SPOILERS)

Pardon me but I always refer to characters by the actor's name because otherwise I get confused.

When I first watched the movie, I was under the distinct impression that Rabal was out to kill Scheider the whole time, which adds to the tension but gets complicated by the bond that grows between them when overcoming so many obstacles together. Many have supposed that he was just sent there to kill the original driver he replaced, but my take was always that he killed him as a utilitarian move just to get closer to Roy. It's a secret his character unfortunately takes with him to the grave.

I think he was obviously sent there to kill somebody because he's got the only flashback in the opening that doesn't end with him desperately on the run. Instead it's a small professional hit job that looks like he could easily have gotten away with.

The argument against him going after Roy is that a second team of hitmen show up at the end of the movie, but then again they could have just been alerted to his failure from an inside source at the company and gone in to finish the job. That's why they brought his friend along to make a positive identification so there would not be any doubt after "plan A" failed.