Lawrence Kasdan, the filmmaker whose credits include the superb efforts The Big Chill and The Accidental Tourist, wrote the script for The Bodyguard back in 1975, during his off-hours from his job as an advertising copywriter.
Costner, who was probably more alive as the corpse in "The Big Chill" than he is here, learned about the script when he and Kasdan were making "Silverado," and for whatever reason decided not just to produce it with Kasdan and Jim Wilson, but to play a role that was originally intended for Steve McQueen.
Lawrence Kasdan wrote the movie in the early Seventies as a first-ever script that took a while to find a home; meanwhile, he went on to write a few other things you might know, like "The Empire Strikes Back," "Return of the Jedi," "Raiders of the Lost Ark," "Body Heat," "The Big Chill," "Silverado," "The Accidental Tourist," "Grand Canyon," and a couple of yawners, "Wyatt Earp" and "Dreamcatcher."