My viewpoint on this is that people do die, and refusing to admit the possibility in stories does omit a fairly important aspect of life.

I've killed off characters in several of my Buffy stories. It's a difficult decision to make, but sometimes it's the dramatically appropriate way to handle things. I'll typically post a warning, though at least once I've done that and killed off a second string character to lull readers into a false sense of security before taking out someone major in a later chapter.

Marcus L. Rowland
Forgotten Futures, The Scientific Romance Role Playing Game