Well, well... the beloved Bella smoking pot... It's funny, I always thougth Kristen Stewart pull the 'broken child' character real good. Now... well, she kind of... IS a broken girl.
This explains her face all the time... now I get it. She must have been really stoned while shooting Twilight... that explains pretty much it.
All I know is that girl with the pipe pretty much clear a few things up for me.