I introduced DS to the classic horror films (original Frankenstein, Wolfman, Dracula) when he was about 7. I made a big deal out of it, popcorn, darkened room, the whole thing, and kind of joked through the scary parts while watching him carefully for his reaction. He loved Dracula, and I heard 'I never drink...wine' and 'Children of the night! What sweet music they make!' for months afterward.