I’m compelled to write about the notion of stealing ideas because it’s something I hear a lot, especially from newer writers. “I don’t want to share because someone might steal my idea.”
A trip in time to steal Harry Potter
Imagine, for a moment, that you are able to go back in time to 1995. You’ve read the Harry Potter books from start to finish. You know the story. And here you are, conveniently two whole years before J. K. Rowling published the first Harry Potter book on June 30, 1997. So you decide to sit down and write the book from memory, because how hard could it be, right?
How do you think you’d do? My guess is you’d end up with a completely different book than the one Rowling wrote, with a different feel, a different voice, different pacing, word use and more. Different because you are different, in other words. In fact, aside from the basic plot being similar, the names being similar, if you sat down and compared your copy and the real thing, they wouldn’t be much alike.
Those ephemeral wisps, ideas

Now that was a whole book and the goal was to copy the thing, by memory, to steal the success of the book–or try to anyway–from the original author. You read the book, knew the characters, their names, the story problem, the locale, all of it. Let’s say you now have only an idea. Here, let me throw out one:
It is possible, theoretically, to make a poison that is DNA specific. That means someone could manufacture a gas that they could then pump into an entire building but the only person affected would be the one whose DNA matches the poison’s coding. Now picture a government with that technology. What would society be like knowing that individuals could be targeted for death at any time? And what would happen if that technology fell into the wrong hands?
You can take that idea and write it however you like. Perhaps I got more detailed with it and said the main character, Charlene Rogers, works on the team who developed the DNA coded poison. She hates her boss and, in a lapse of judgement, takes the project notes and plants them in the boss’ office so he will get blamed for trying to steal them. (Charlene isn’t too savvy with her planning.)
The only problem is, the boss has been trying to work out how to steal the thing anyway, because he wants to sell it to terrorists willing to pay a mint for it. It falls into his hands and he’s delighted. He skips the country and leaves Charlene hanging, maybe literally, because what she’s done is probably considered treason. Now Charlene must go on an eight country chase to retrieve the plans before the terrorists can use it.
(Yes, I’ve considered writing this, but I’m not sure thrillers are my strong suit. Or all the science and tech. Still.)
The point is, I am not worried that you’ll steal my idea because if you take it and run with it and I decide to write it too, there’s no way in hell our end results will look anything alike. And, I hate to tell you, there aren’t any truly original ideas. It’s all in the voice, the execution, the prose. Those are the things that make one story stand out from another.
There’s a reason why we have a tropes website … many trope websites
What is that reason? We humans keep going back to the same ideas over and over because they resonate with us. We like the coming of age story, or the romance, or the hunt and chase story. Those are the skeletons on which our fiction hangs. But, just as there are billions of unique individuals on this planet all hanging off very similar skeletons, there are trillions of original stories hanging off similar framework.
Think of some of your favorite stories. How many are the same idea told in a different way? For the love of all that’s unholy, how many versions of Batman have you seen? Same story but a different interpretation each time.
Basically what I’m trying to say is: don’t worry that someone will still your idea. Truth of the matter is, you probably lifted it off someone else, whether you know it or not. As long as you aren’t plagiarizing–which is a bad, bad thing–you’ll be fine. FINE I TELL YOU!
(Besides, who says your idea is so fantastic I’d want to steal it, anyway? Yeah, it fires you up because it’s sparked something inside you. Since we’re different, though, we probably don’t get excited about the same things. Except for bacon. Bacon is the exception to everything, I’m fairly certain.)
Wait, I think you stole my blog post!
Hahaha! Maaaaaybe. 😀