Like most people who own their own businesses, I work long hours that start early in the morning. So when someone calls me in the middle of the night, they'd better be dying. "Hello, Mercy," said Stefan's amiable voice in my ear. "I wonder if you could do me a favor." Stefan had done his dying a long time ago, so I saw no reason to be nice. "I answered the phone at"-I peered blearily at the red numbers on my bedside clock-" three o'clock in the morning." Okay, that's not exactly what I said. I may have added a few of those words a mechanic picks up to use at recalcitrant bolts and alternators that land on her toes. "I suppose you could go for a second favor," I continued, "but I'd prefer you hang up and call me back at a more civilized hour." He laughed. Maybe he thought I was trying to be funny. "I have a job to do, and I believe your particular talents would be a great asset in assuring the success of the venture." Old creatures, at least in my experience, like to be a little vague when they're asking you to do something. I'm a businesswoman, and I believe in getting to the specifics as quickly as possible. "At three in the morning you need a mechanic?" "I'm a vampire, Mercedes," he said gently. "Three in the morning is still prime time. But