ON the morning of Saturday, Feb. 26, a day before the Academy Awards, the actress Carrie Fisher woke up in her Beverly Hills home next to the lifeless body of a gay Republican political operative named R. Gregory Stevens. Thus ended one of the more improbable friendships that Hollywood and Washington have known - and a globe-trotting, adventurous, but ultimately debilitating existence that might be fodder for a Tinseltown thriller, if it only had a satisfying resolution. Before its abrupt end, Mr. Stevens's journey had taken him from the beaches of San Clemente, Calif., and the slopes of Sun Valley,...