I write originals, and will freely admit to using character shields. It just seems right to me. This doesn't mean that I won't kill a character or two, but it does mean that their deaths tend to have a time, place, and meaning. A good example is one of the two stories I am working on. One of the characters is going to die, and because of the way things worked out knows not only when, but where and how as well. The rest I expect to always survive, so they will, even if it means monkeying with the rules.
The other fic involves lots of space fights though, and since that is the one I am posting, there will be plenty of people with names going up in flames.