Particularly with YA, we are a little obsessive with our trends. We latch on to them and then people get tired and then quality downgrades with mass production within those trends and then we find something else and it all starts all over again. That, or we have tropes so deeply ingrained in us that they just crop up and we can do nothing else but throw up our hands and hopelessly theorise about what we could have done to avoid this.
Everyone tries to put something fresh on old plots, or common plots, and make them work and brilliant by their own standards. But, especially with these YA trends, sometimes it's the core idea which traps us writers and inhibits our ability to see beyond the seeming conventionalities of said trend.
Here's one. Let's see if you can name it.
A seemingly normal girl encounters a mysterious, gorgeous boy who sucks her into a supernatural plot which endangers her life but entwines her fate further with his when threatening elements converge on her town-slash-city.
There is a whole universe full of titles you could be throwing at me right now.
TWILIGHT is probably the most common.
Or, even HUSH HUSH. Or, VAMPIRE DIARIES. Or FALLEN.
CITY OF BONES.
While they have similar, even identical, elements in common, each of those other books are different from one another. But CITY OF BONES is almost intrinsically different. Don't get me wrong, it has its problems and it borrows heavily from a number of trends and moulds. The girl meets supernatural boy is just its premise, not its story. It goes much deeper than that, and that is exactly what separates it from TWILIGHT.
Bella is passive, and doesn't have direction beyond the premise. Clary's journey is sparked by the premise and unfolds into a deeply personal endeavour on her part, where she actively engages in the conflict and sways it back and forth.
Do another one yourself. Like, the dark lord concept with only a plucky hero to face him. What could that be? HARRY POTTER? ERAGON? What?
If you're worried about this, you need to think beyond the premise. Beyond the book.
You need to isolate the exact premise, figure out the conventional chronology of plot points. Once you've done that, if you've cross-checked a couple examples and made your list, you need to start brainstorming what isn't on that list.
Character: is there one who can be involved who is completely different to those previous? What traits haven't been used yet? Why do they have to only be a century old, why not millennia, or why not a newborn who's only a few decades ahead of their physical age? Why do they have to be gorgeous and charismatic? Why not overly intelligent or socially stilted?
Setting: is there somewhere more fitting for your story? Would an angel encounter be more fitting in Vatican City? Or in an Orthodox community somewhere in Eastern Europe? Or even in a Catholic school somewhere in Asia or Africa or South America? Can it be in the past or the future? (And by past I don't necessarily mean the 1800s, it could be the 60s!) Does it have to be in a city or a small town? Why not a small city or a town with heavy tourism traffic?
Perspective: are you telling the story from the right perspective? Should it be from the human or the supernatural side? Or should it be a rebel against a dystopian government and not a government official struggling with their beliefs in this conflict?
Genre: could you meld genres here? Could you bring horror elements into a demonic story? Could you combine a murder mystery with ghosts, like Maureen Johnson?
As far as tropes go, you could turn things on their head, or challenge do's and do not's. Could you look at tropes that belong in other genres or other trends and explore that? Could you not have an uprising against an oppressive vampire governing-body as your main plot, with your naive heroine thrown in at the eleventh hour?
We've all done it: click out of a tab in frustration because why didn't we think of that spin on that idea. People always find ways of doing it, and there is no reason why we can't challenge the YA audience to spread the reach of its trends with our spins and concoctions.
Have you ever taken a trunk novel out with the intention of reviving it with a spin? Have you ever stepped back from your novel and fundamentally changed its concept and plot? Have you seen books where the author has tried and abandoned their attempt to subvert conventions?