What really possessed Regan MacNeil? As a young husband, I would be shocked every 28 days or so by the demonic possession of my beautiful bride by cantankerous imp who I came to know as Aunt Flo. In spite of having grown up in a home with three younger sisters, the vituperous arrival of my late wife’s monthly visitor never ceased to surprise me. I’d walk through the door wearing a hopeful smile after a long a day at the…