Funny you should mention that. I said in some blog post on this site, years ago, that far more of the novel is based on my real-life experience than most readers would expect. I had this incident in mind, among others.

Since then, aspects of the book which were entirely imagined have come to life. H. P. Lovecraft said that this is an occupational hazard of writing horror fiction. I think it was Neil Gaiman who quoted him saying that, and Gaiman said his own life had confirmed it.

A few years ago, I was with my sister in hospital as she was dying of cancer. Blood was pouring from her mouth... apparently, profuse bleeding from the gums is common at that stage.

"She looks just like the cover image of Buddhism for Vampires," I thought. I thought that was really funny.

You probably aren't supposed to find anything about your sister's dying funny, but I don't think she would have minded.