I don’t know if this might help you, but there are some pretty nifty sites out there that can retrieve web images based on descriptions, sketches and even other similar images.

One that I used recently to get a tattoo design idea is called Retriever it’s just a free site…

You can literally sketch in an image and it will scour Flickr for similar images. I used it to find an orchid in a specific position. Pretty cool.

I don’t know the URLs to some of the others but a quick Google search will help.

Good luck!

Alternatively have you considered looking at the Neil Gaimann graphic novels for the sandman that would fit the desc nicely.

There is also many sites devoted to darkside anime that may also fit what you are after.

Take Care
Matthew