The idea of the story I'm working on is that: four foster kids live with a very strong warlock who adopted then when they were babies and trained them. They are all fifteen and in three years, they all ascend and reach full power. In the mean time, they have to deal with demons, vampires, and other warlocks. And they also learn about a plot that involves them and demons.
I don't know. It sounds kind of...cliche. I mean, if you can make it your own, you might have a truly groundbreaking story here. But from the summary you provided, it just feels like it's been used. Having demons and fantasy creatures as enemies are a good antagonistic force, but they'd have to be your own creation. You know what I mean? Just try to avoid the pitfalls of a story about wizards and magic, and you've got an ace-in-the-hole.
A story concept means nothing. I can tell you now, it has been done before. What matters is how you write it, the characterization, the flow, the imagery, all of it. There's no point to asking what other people think of the concept! They'll either say,"Sounds great," or, "it sounds kind of cliche" If the idea stirs you, write it. Then ask people what they think of the final story. After they tell you what they don't like about it, revise it, usually several times, until you're happy with it or until you throw up your hands and say the hell with it. Please read this thread about What is Plot Creation and Development? (and yes, this is a template post, which should give you an idea of how often this comes up.)
Yeah. It really comes down to what the final product becomes... Just write to the best of your ability and DON"T procrastinate, or else you'll never get it done. (I know from experience.)
