If you want to copyright an idea, then you should first know that you cannot do so. The very process that governs the creation of a copyright, with regard to international copyright law, is that it happens when a work of art is no longer an idea and becomes something real. This means you can copyright a work of writing, music, or other artistic expression simply by creating that work and no longer merely having it as a concept. The process of creating a copyright therefore precludes the ability to copyright an idea.
A copyright is a form of ownership and protection that would commonly exist for physical property, such as land or a vehicle, which is extended to intellectual property such as artistic creations. This means that for you to have protection of a piece of work under copyright law, you must actually create the work and not have it only as an idea or concept. If you could copyright an idea, after all, then anyone could simply claim that they had copyrighted any work created by another person as a concept. International copyright law does not require that you register your work with a government or agency to have copyright protection, which means that there is no central location where you could submit a form to copyright an idea.
You gain copyright protection simply from the process of turning an idea into a realized work of art or creative expression. The fact that you cannot copyright an idea is why there are so often similar works of art or creations that seem fairly derivative of each other but do not infringe on any copyrights. If a writer could copyright an idea, such as “the protagonist falls in love with the character he or she had been fighting with previously in the story,” then there would be a tremendous number of artistic works found infringing upon whoever held the initial copyright.
It is also worth noting that you cannot copyright certain story concepts, names, or other aspects of a piece of artistic work. You cannot even copyright the name of your work; this is true of films, books, paintings, and any other copyright protected work. There are, after all, long lists of songs with identical names. The names of original characters and works of art, however, can be trademarked and protected under the statutes and regulations involved with trademark law. This is typically not necessary, however, unless your characters become especially recognizable and others begin to use their names to profit from your creation.