I had an idea about 2 people going to investigate a haunted mansion for a news piece(Or they're ghost hunters.) Soon after they enter, they are locked in with a spirit that craves their life force. So not only is the mansion coming alive and trying to trap them, it is also repossessing both characters from time to time in order to fornicate with the other.
In essence, it's like John Carpenter's The Thing meets The Entity, where the characters start to get suspicious of the other being possessed and even attempt to kill each other.
In essence, it's like John Carpenter's The Thing meets The Entity, where the characters start to get suspicious of the other being possessed and even attempt to kill each other.