In the right context, your idea sounds very playful to me.
Considering “Ideas” as your main character, there are different metaphors for it that one could dig up. Let us look at an idea. You said the main character is an idea that is trying to help a writer. Some ideas deal with imagery and are therefore ascribed to the sensing parts of the brain, but the more abstract concepts (like Love and Wisdom) are metaphysical concepts that deal with non-material functions, or if one is a materialist, it is a gas or excretion of the brain (not so glamourous of an explanation this second).
But following along with the above, ideas can inspire, give one a push toward a right direction, the “Aha”! moment in which all things suddenly come together as a unified whole. So your idea has the ability to inspire the writer, to put random pieces together into a cohesive whole.
What symbols can we apply to Idea since it is an abstract concept rather than something we imagine? Or even better yet, what images have been used? You said you could use some inspiration- Light, doves, lightbulbs, cloud, mist, seem to convey different aspects of inspirations or illuminations. To be illuminated is literally to be lighted up, to make that which was dark, clear. You can see how this can apply to our mental activity.
The word inspire itself literally means to spirate forth, that is, to breath into something, a breath, with the connotation of giving life. Thus your idea is something that will breath life into the writer. Perhaps a floating coloured glowing light, sort of like in the BFG movie, like a sprite or fairy, would be of some utility? This would then take both concepts of illumination and spiration and attach it to a sort of metaphysical/fairytale like form that would inflesh your “idea” with physical form. Simple point of light is all that is necessary if one wants to.
Thus it could be that a fairy or sprite (some form of floating light) wonders about the world seeking writers/poets/musicians to inspire.