I've decided the artists are a girl named Emily and a boy named Oliver. Oliver was trying to impress Emily by taking her to the destroyed house, because he suspects that all-black wearing Emily probably enjoys trouble. Emily plays along and spray paints her signature hearts and smiley faces a few places. Oliver is oblivious to the fact that her markings have already been made in several rooms on previous occasions, because this is a regular haunt for Emily. Like a pretty spider sitting in her invisible web, she's caught a fly...
Alright it's almost midnight here and that's enough story time. You finish it in your mind - I'm sure you can work those broken chandeliers and the coffin in there somewhere.