It's a lie!!!!
I have read the book and I think the movie had changed somethings to make it more dramatic for television.
In the book I had the feeling Steven actually enjoyed being molestated,it sounds horrible but I got that from the book.Ok not that he enjoyed but that Parnell had done it for so long to the poor kid that he didnt feel anything after a while.And in parts of the books Steven said himself that he felt love for Parnel(wich in my opinion makes the book more disturbing than the movie),and there his allso the fact that he didnt want to be found,he was not retarded as a teenager he knew that he was being molestaded,yet he never tryed to see if he could find a better life.I dare to say that Steven had an other motive from bringing Billy to the police,I think he was jealous that a new younger boy was taking his place.
From the book I read the story of a regular young boy that got brainwashed into becoming a sex slave and at the end totally got used to it,he even let Parnell screw his freinds/neighbour up.I felt that by age fourteen Steven was happy with this sick way of living because he simply didnt know better and once he got home he wasnt happy,he wanted to see Parnell again.
But for the movie it has been modified for us to feel sorry for Steven ,somme parts of the books were cut off and funilly it was the parts that helped me geting a bit of disliked for Steven.
I think there was far more to the story than what we see in the movie and the relationship between Parnell and Steven was not just good vs evil but was far more complex than that.