Did you know you can't copyright an idea? Anything you write is automatically copyrighted to you, but only the words themselves, the ideas can never be copyrighted. However that's okay, because no matter how original you think you are, the idea has been done before.
In fact, that's the great thing about ideas, plots, tropes and clichés. They're free for everyone. The other good thing about them is that if people love a plot, trope or setting, they're probably going to go looking for other books, movies, TV shows and comics with that same idea.
Writers get asked where they get their ideas all the time. The true answer is probably something like: 'Cultural narrative is a concept and tradition that has been passed down since mankind developed language'. We don't 'get' ideas. We 'reuse' ideas.
I think when writers tell would-be writers to read widely, this is one of the important reasons why. Sometimes I meet people who don't read much, or maybe they only read one genre, and they are often convinced they have a really, truly original idea. They're nervous to share it with me. It's always ultimately a huge cliché in a genre they don't read/watch. One that has been done to death, but they have no idea.
A woman in her 50's once told me about her 100% original, never been done before plot where a person from our reality passed through some kind of gate or portal into a fantasy setting. No really. She was super offended when I said it was its own subgenre.
So really, when someone asked me where I get my ideas, the answer is: I mush together a couple of things I love into a new Franken-plot. Take the plot from Die Hard, shove it into the setting from Avatar and then stick in my favourite characters from Psycho Pass and Ouran High as love interests and BAM, that's a novel right there.
Notice I didn't just say I was re-writing Die Hard, I took elements from a bunch of places, themes and ideas that I liked and wanted to play with. This is how you come up with ideas. However for a lot of writers this comes so naturally, it's hard to see what we are doing.
David Farland addresses a similar idea in his book 'Million Dollar Outlines' and calls it resonance. I highly suggest reading his book and even listening to some of his interviews on youtube. Resonance is when ideas remind us of, and build on the culture that comes before in order to give readers a call back memory to other things they have loved.
I think some writers are deathly scared of using ideas that are 'too similar' to other works. Pro tip. Your idea, whatever it is, is similar to other works. If you don't know what they are, it's just because you haven't read them yet. No one cares. Its fine. Once you get over that fear, 'finding' ideas is much easier.
Recently, Meg and I greatly enjoyed watching Yuri on Ice (check it out on crunchyroll if you haven't seen it already), a gay romance about competitive figure skating. Instantly, we knew we wanted to play with the idea. So we wrote a gay romance about a figure skater and an ice hockey player (Bite the Ice). Because we were so enthusiastic about the show, it only took us two weeks to write a complete novel, which is now in editing.
Currently, we are writing a book that is based on an idea I had when I first watched frozen. However instead of a princess fleeing her home to hide her magic powers, it is about two brother magi who were driven out and hunted for years, but now the people who persecuted them are begging for their help to save them from an even bigger magical threat (As Light As Ashes).
So if you are struggling to come up with ideas, read more, watch more, play more then take a handful of the ideas you love the most and jam them together into something new. If you love things, it comes through in your writing. And I can promise you you are not alone in the tropes and ideas you love. Other people who love the same things are looking for more. Your fans will be the people who love the same things as you, and that is an awesome situation to be in.
So go forth, write the things you love.
Remember, you can't copyright an idea, so stop worrying about it.