I recently completed Heavy Rain, but now I'm curious as to what effect my choices and actions had on the story. Is there a breakdown of all the possible paths and branches that the story in Heavy Rain can take out there somewhere?
The FAQ/Walkthrough of AboutLastNight5 at GameFAQs.com lists all possible endings together with a list of the conditions that must be met to achieve them.
Of course, the guide includes major spoilers and you will have more fun replaying the game without this guide.
Most of the branches have smaller effects than you'd expect until late in the game. For the most part, you'll still play all the same chapters. If you don't mind spoilers, I'll go into detail below...
There is a great guide to getting the All Endings trophy at IGN that I used. (Obviously, it will contain spoilers.) You basically play through once, going for the "perfect crime" trophy. After that, you only have to finish the game six additional times, and you don't have to backtrack any further than the love scene. After getting "perfect crime" ending, I think it took me about 2-3 additional hours to get all of the endings--with a hefty chunk of that time spent watching the credits.
Beyond that there are tons of little differences in the dialog but they don't really affect the larger story.