Built on cursed land, Rose Red was thought to be "born bad", as even before it was completed, severel workmen died under strange circumstances.
The house itself -- or rather, the force behind it -- can be described as a parasite that drains both life and spiritual energy from its victims. First, it drains the victim's life energy by killing him/her and then feeds off of the spritual energy of the his/her spirit.
The force inside the house was very unpredictable. When the house was still occupied by the Rimbauer family, it took a victim whenever it pleased; its favorite victims were female. It took Ellen Rimbauer's daughter, April, to remind the woman who was really in charge.