I like a good horror movie, and ORPHAN is a pretty good up until the end, when, like in most horror movies, the killer becomes an indestructible terminator.
This movie has been touted as having a shocking twist in it. Since the movie is about an evil young girl who is adopted by an unsuspecting family, I figured there were only 2 or three possible "twists" the movie could have.
1) The little girl turns out to be an alien
2) The little girl turns out to be a ghost
3) The little girl turns out to be...something else.
Since the movie did not seem to have any supernatural elements to it (based on the trailer), I figured it had to be "something else." If you think about the premise for about 2 seconds, you should be able to figure out what the "something else" is.