What Luke’s father and Darth Vader would have been like had Lucas kept them separate?
You can find out by reading Leigh Brackett’s first draft of Empire Strikes Back. In this early 1978 version of the movie, Vader is not Luke’s father. Also, Luke’s actual father appears to Luke as a Force ghost. Luke’s father is portrayed as a stereotypical wise old Jedi character, very similar to Obi Wan.