If you saw Fantastic Beasts and you were like me and probably 95% of the audience, you knew the moment you saw Jacob's briefcase that it was going to be mixed up with Newt's. Similar things have happened in dozens if not hundreds of stories--usually in film and television. It's a trope, one used so many times in such identical ways, it feels cliche.
But as I mentioned in my post Using Cliches in Your Writing: Why, When, and How, there are three ways to get away with pulling off a cliche: personalize it, put a fresh spin on it, or use it to draw your audience into a surprise.
Another way that overlaps with these is to change the temporal (meaning timing) of the trope. Rowling may have used this trope, but she understood she was using it, and decided to take advantage of that to tease her audience. (She makes a point to do that every once in a while, if you haven't noticed.) So she has Jacob run into Newt, both dropping their suitcases. This is the traditionally prime moment to have the whole mix-up happen. This is where it happens in almost all films and television shows. Rowling knows this. So she teased us with it.
So much is happening with the Niffler and characters, that we get distracted and forget all about the trope we're waiting on. Poof. It's gone. Once again, Rowling used distraction, bringing elements into the story that demand more attention. Oh no, a Niffler is loose! Oh no, Newt performed magic in front of a Muggle. Wow, his creature egg is hatching. But it's in front of a Muggle. That lady is following him around. Crap, now the Muggles think they are stealing money. They've sounded the alarm. (By the way, is having a Niffler get loose in a bank not a perfect idea?)
Rowling uses Misdirection. She puts down the dots of the briefcase mix-up, but hasn't connected them yet. Instead, she leads her audience off the trail. We're so encompassed by her distractions, most, if not all, of us completely miss her sleight of hand. Most of us forget about the trope.
Next thing we know, Tina is taking Newt in to the MACUSA as a lawbreaker. And by the time Newt's briefcase is opened and it shows pastries, the trope has become a surprise again. I even heard audience members behind me gasp. In short, Rowling took a tired, worn trope, teased us with the expectations, lured us into ease, distracted us, then delivered on it.
Notice, too, that when Newt and Jacob actually do mix up their briefcases, it happens in the background. Whereas usually with this trope, it happens front and center. We see the characters hit. We see them grab their items. They're on their way with the wrong items. It may have been subtle once, but stories have trained us through storytelling patterns what to expect. It's not subtle today. It's front and center. But Rowling put it back in the background.
But one of the great keys to all this, is to move the trope's timing. Rowling teased us with the expected timing, and then actually moved the real timing so that it happened later in the story. This can be really effective. Because again, you are playing with your audience's expectations, luring them into ease, and then surprising him. I noticed this exact same thing happen the first time I saw Half-blood Prince. Remember when Harry has to get water for Dumbledore? The filmmakers did a great job of feeding into our expectations (which is that an inferi is going to get Harry). Watch the camera angles, the way they draw out shots, the way they exclude specific areas from our sights by the perspective of the camera.
As Harry's arm lowers to the water, as an audience, we subconsciously know, this is the traditional moment something pops out and grabs him. Back in the day, that was the perfect timing. Someone is reaching into a lake, doing their own thing, and just before they touch the water--surprise! I'm sure back in the day, no one saw it coming. But today, we've all been conditioned through story after story to expect it. Also, in this particular Half-blood Prince scene, the audience is already expecting it because we've already had the foreshadowing and set-up of seeing the inferi in the water. So what do the filmmakers do?
Move the timing.
Harry's hand actually breaks the water. He fills the sea shell. He even begins to bring his arm back. By these tiny, tiny actions, the filmmakers are luring us into a tiny bit of ease or if nothing else, making us doubt on some level our initial expectations. Maybe nothing is going to pop out.
And just at that moment, Harry's arm gets grabbed.
The filmmakers cleverly moved the timing. You can do this too. Some people feel we should never use tropes (if that's possible), that we should never use cliches! But look how great they can be if we use them to our advantage, use them to play with our audience's expectations. And if you want or need to use them, look at how you can use them in new ways, or ways that won't generate groans.
Temporally moving the moment can work in the other direction too. You can move the moment up, so it happens sooner, and that can be surprising. It can also cut down on the length of the audience's expectations, so that it happens even before they expect anything. And that's surprising.
You can do this on a micro-level or a macro-level. If your character has goal, and reaches it halfway through the book instead of at the end, the audience is left wonder what happens next. (In that case, reaching the goal must lead to even bigger problems in order to keep the story going and building.) As writers and creatives, we could play with our audience's expectations so much more, and so much more effectively, but it seems as if almost no one does. Take advantage of these things. Use them effectively. It can make your story unforgettable.