Your opening scene has one very important job if you are unpublished and want to sell your work. To get off the slush pile at the agent or editor you’re trying to catch, you have to promise in as few words as possible that this plot is unlike all the other plots with similar themes in existence. There are only so many stories in this world, but you have to be able to promise (and carry through with that promise) that this book is going to grab the reader’s attention and keep it, hook, line and sinker.
But I think the habit of starting a story with a wild hook has gotten so ungainly that the more quirky and weird the hook is, the more I feel I see the author’s thumbprints all over the writing.
Your first chapter sets an interesting character in an interesting world with an interesting problem. the main character has to want something, and the events of the opening scene should set the MC on the course of the plot of the book.
In media res I think also has to be done with a more deft hand than beginners usually can muster. In order for it to work, the strands of the world building, the character’s development and the explanation of what his happening has to be in a seamless french braid that picks up the strands of the ongoing problem with all that you’re trying to braid in already.
If you can do that, great, have at it. If you let one chunk get larger than all the others, all you end up with is a lumpy, bumpy mess. You’re trying to describe the main character and his problem. Stopping the plot to explain the reader why the thing is happening, whether or not it’s a good thing and what the MC is hoping for as an outcome is a terrible amount of balls in the air.
The last thing you want to do is open the book with a person weeping after a battle. For one thing, it’s as cliched as anything and you are going to have to compete with all the books in the slush pile that also start after the battle is over since 10% of unpublished books start this way, and secondly, we don’t know if this character has lost someone or if there’s no one left to kill.
I think that your book should start with a bang, but it should be at the end of the third chapter. By the time you get to that big, emotional scene, your reader and your main character are literally on the same page. They should know the best/worst outcome and why it’s such a big deal. By the end of the third chapter, your characters should at least have a grasp at what the bigger problem is, even if that’s not the big issue yet.
I always like to use the AIs from The Two Towers. The programmers gave the characters different levels of intelligence. The smarter the AIs were, the more they took one look at the forces that were against them and ran in the opposite direction. Your character should be smart enough to look at a huge problem like an entire iceberg that they have to melt down with a hair dryer as being way above their pay grade and, more importantly, Someone Else’s Problem. The problem that the MC should see should be more like the tip of the iceberg. Still big, but not SEP big.
The best part about using the the iceberg problem, you as the author do not need to know what the bigger problem is before you start. Your MC discovers something interesting and decides to follow up. All you have to do is follow him and keep throwing roadblocks at him. The more the story develops, the more what the bigger problem under the surface is. By the 3/4 mark, you, the characters and the reader should know exactly why that weird thing happened in the beginning.
On the rewrite with this method, you have to go back and put the characters as you learned who they were at the front of the story. You need to shave off any plot trails that you didn’t go down and hide hints as to what the real problem is in the early parts of the story. Don’t be alarmed if you have to change the beginning entirely or you have to carve off the first chapters until you get to characters actually acting on the problem. A lot of the time the characters change so drastically between the beginning and the end that the new beginning demands a new end.
Don’t think that any rewriting as lost work. The idea that you started with has probably occurred to dozens of other writers. Your story becomes unique when it becomes the story that only you can tell. If that means ditching the last 50k and rewriting it according to the 2 am flash of brilliance that came to you just as you were falling asleep. It’s those moments that are the fresh, new idea.
I use this example a lot, but your book is probably going to be read by an assistant before it gets to the real name on the envelope. You have to imagine them desperately looking for something that will knock their boss’s socks off after they get back from the lunch. You want to make sure that by the time they get to the third chapter they’re reaching for the phone to read the rest of the story. We’re an extremely jaded audience with only a tiny fraction of money and time to spare for books. If your ideal reader is only going to buy three books next year, show your first reader why one of them should be yours.