A while back I had the same question and got a lot of help, so if you check the posts the Information is there.
I will try to do a walkthrough on the go:
- For corruption path choose answers that give corruption points and when asked degrade relationship with Brian - all the time.
- For blackmail path choose answers that give corruption points and when asked degrade relationship with Brian untill you reach 6 true points with Brian. After that you must choose answers that give corruption points but stay within 6 to 8 true points with Brian. That is done by choosing stay true once and the other time degrade relationship.
- For purity path you have to choose answers that do not give corruption points and stay true to Brian. This path will end soon, as stated by 3Diddly, and a new path added. It also has the least sexual content.
Hope this helps