In most books or movies if you can identify the love interests depending on genre then you can just about figure out who will live and who won’t. The two people that are in love and trying to have quick Sex in the middle of everything are usually two of the people that will survive. If you are a side kick character then you have a fifty fifty shot at it and you’ll definitely have to fight to survive. The main characters just have to sort of go through the motions. It’s become a formula of easily predictable survival ratio’s.
If there is a sort of secondary main character or supporting character that seems to make it through a lot of stuff, then you can count on that person buying it for shock value two or three books into the series. This naturally propels the main, main characters back into the fray to avenge the death or whatever. Occasionally there comes an author who tries to turn convention on it’s head and surprise you with a twist such as writing from the perspective that the monsters, or the bad guys, are actually the good guys, and the good are bad, but even that’s been overdone. What’s more rare is the author who is able to succeed in truly surprising the reader with very unforeseen events. They may have characters that are set up to be seen as the heroes and then have them bite it early on and leave you completely at a loss for what’s going on. Then they offer up a potential hero from a reformed villain along the way and really get the thrills going.
Then if there are love interests and Sex it’s unexpected and your definitely unsure as to what may happen. If two people are fucking and becoming love interests, they might still get killed. Just being love interests or singles wanting to become couples doesn’t immediately buy characters a safe passage in that story, and it makes it all the worth while to read.