What the heck was all that crap I just saw?? It didn't make ANY sense!
It looks as tho it could have been a spooky story & a spooky movie, but someone (probably that director) screwed it all up.
I don't know what Lena Olin's problem was, either. I always thought she was an ok actress, but she worked so woodenly in 'Darkness' it seemed she was acting with a big stick up her butt.
TOTAL crap.
The movie makes plenty of sense if you paid attention. Regina's Father was the seventh child that escaped years ago from being sacraficed. He started having flashbacks moving back into the House. Regina's Grandpa needed Regina to cut his Throat (because it needed to be cut by loving Hands)
This is why he lets Regina go and only drugs Carlos ininstead of killing them both. The Darkness manipulates both Regina and Carlos in the end killing them presumably unleashing Hell on Earth.
The reason Regina's Father also acts out is due to hs Father giving him bad Medications as his Dr. Once the secret room and Blueprints were found Regina realized the House she was living in was engineered for the sacraficial ritual. The house was haunted by the previous children who were killed plus Demonic energy.
As for Lena that was how her character supposed to be like. She is stressed out by her ailing and borderline psychotic husband and cynical daughter.