First of all, I love the concept. Characters literally bullying their creator into finishing their stories? Win! (now lets hope it never happens to me... O.O)
I like how Greg spooks himself into doing something he knows would be stupid in a story setting. I have to say, though, I was surprised Victoria didn't make an appearance until the end. After all, she was the reason he went downstairs in the first place (or was it just down the hall? I can't remember) and, given that his first reaction upon turning on the light was to graphically spill his guts, I was really expecting him to find her murdered-and-possibly-dismembered body on the kitchen floor. I have to say that it's a bit of an over-reaction, especially considering that he knows these characters intimately. Granted, they're a gruesome lot, but still. He wrote it, after all- a fact which they fling in his face repeatedly (again with the win!
).
You give the impression that we should be familiar with these people, much like a fan-fic. And like a fan-fic, it would probably be more fun to read if we were. But it's also ok if we aren't- if that makes any sense- because you give us enough description and interaction to solidly establish their characters. So good job there.
***(Please don't be offended at me comparing this to a fan-fic. I know there are a lot of authors and editors and critics out there who roundly disparage fan-fiction of any kind. However, I think it has it's place, if only on the inter-webs. So yeah, no slam from me, there. And not a back-handed compliment, either. The style, kind of tongue-in-cheek if you will, just reminds me of it.)
One thing that bothered me, though... you repeatedly mention him mumbling into his beard. Now, I might be mistaken, but I would accept this description more readily if you at some point mentioned that his mustache had gone untrimmed for so long that the hairs had merged with his beard. Otherwise I get a mental image of him physically holding up the beard to his mouth like he's got a radio in there. Just a personal preference, though.