The silence in the grand, unfamiliar house was a living thing, vast and echoing. My new parents, so kind and overwhelmingly cheerful in their efforts to make me feel at home, had left abruptly for an emergency business trip, leaving me alone with him. My stepbrother, Liam. We hadn't really talked since I arrived a week ago. He was older, maybe twenty-one, with a quiet intensity that was both intimidating and strangely captivating. His presence just loomed, even when he wasn't around, a constant, heavy weight in the air.

I’d sought refuge in the master bathroom, drawn by its sprawling tub and the promise of scalding water. I slid into...