On the surface, Quantum Immortality is an attractive thought.
Under the many-worlds interpretation of quantum mechanics, every chance event leads to the creation of multiple parallel universes. When you roll the die, it doesn't come up 5. It comes up six different universes, and your personal thread of causation just happens to be looking backwards from the perspective of the '5' branch.
As a corollary, if you are ever in a life-threatening situation and there is a possibility you might survive, in at least one universe, you will.
Sheldon: Penny, while I subscribe to the "Many Worlds" theory which posits the existence of an infinite number of Sheldons in an infinite number of universes, I assure you that in none of them am I dancing.
Penny: Are you fun in any of them?
Sheldon: The math would suggest that in a few of them I'm a clown made of candy, but I don't dance.
– Big Bang Theory: S3. Ep3. The Gothowitz Deviation
This leads to the superficially awesome thought that, at least subjectively, you can't die. Your subjective consciousness will always be looking back through that path of causality in which you survived.
This would be great if existence was a binary state between being dead, and being perfectly healthy and able.
Except It's far more likely that as time increases, the number of universes in which you are not a brain in a jar, screaming your insanity into an eternity of nothingness, approaches zero.
Contains Game of Thrones spoilers.
Just after the infamous “Red Wedding” made its way from the pages of his novels onto the HBO TV series Game of Thrones, author George R. R. Martin was interviewed by Entertainment Weekly:
ENTERTAINMENT WEEKLY: How early in the process of writing the book series did you know you were gonna kill off Robb and Catelyn?
George R.R. Martin: I knew it almost from the beginning. Not the first day, but very soon. I've said in many interviews that I like my fiction to be unpredictable. I like there to be considerable suspense. I killed Ned in the first book and it shocked a lot of people. I killed Ned because everybody thinks he's the hero and that, sure, he's going to get into trouble, but then he'll somehow get out of it. The next predictable thing is to think his eldest son is going to rise up and avenge his father. And everybody is going to expect that. So immediately [killing Robb] became the next thing I had to do.
There are a lot of very good reasons to kill a character. Maybe the death of the character is necessary to take the plot in a particular direction. Maybe you want to explore how other characters deal with the death, how it changes them or how the character's absence opens up new possibilities for them. Maybe the character's arc is fundamentally tragic and can only end in death.
“I wanted to surprise the readers” strikes me as a really bad reason. It's soap opera writing: start with how you want your audience to react then work backwards, poking the characters with sharp sticks until they fill in the details.
I’ll be the first to admit that fantasy writing is terribly formulaic, and so laden with predictable plot lines and character archetypes that you can tell from the first page exactly what will happen on the last. David Eddings made a very successful career out of writing exactly the same story over and over again, so well so that over the years he got more and more efficient: condensing the One True Plot from five books down to three, then finally being able to knock the whole thing over in one volume.
This leaves a lot of room for authors to take a machete to the genre's thick undergrowth of tropes, but subverting a trope is a means, not an end. It should be a way to say something new, or at least something newer than “Ha! You weren’t expecting that!”
Also, leaning on your subversion too often can put you in the uncomfortable position where you’re as predictable as Eddings:
So Martin kills off beloved characters in order to subvert reader expectations. But after the first two times, what does the reader actually expect? What if you’ve read Wild Cards and find Martin’s debasement and slaughter of protagonists not only not surprising, but pretty much Martin’s stock in trade? Are reader expectations still being subverted then?
I’m sure Martin has a lot of other reasons to do what he does to his characters. Killing Ned Stark created a power-vacuum that was very important to the plot, and both isolated his children and forced them to learn to live without their father and protector. It’s just telling that when put on the spot, the author picked this reason out of all possible reasons to explain it.
Which is why I think I'll stick to watching it on TV instead of catching up with the novels. If you're going to follow a soap it may as well be a TV soap.
(And it may as well have frequent nudity.)