Here is an interesting video from French-Canadian Artist, Steve Spazuk, showing how he makes art using little more than fire.
It's easy to forget that even modern mediums, such as vine charcoal, are nothing more than sticks and vines burned in a kiln. By exposing the paper or canvas to a flame, Spazuk is essentially creating a fine charcoal film directly onto the surface of his image, which he can then carefully modify with the use of brushes and scratching point.
My son uses an improvised charcoal stick to draw an image.
This technique of creating an image with a flame is called 'Fumage' or 'Sfumato', and was popularized almost a hundred years ago by the Surrealist painter Wolfgang Paalen. Even Salvador Dali implemented the technique on occasion. The eerie, nondescript images that the technique creates were perfectly suited to the dream-like sensibilities of the Surrealists.
Below, you can see how Dali implemented Fumage into his painting 'Autumn Cannibalism' in the upper right corner before working back into it with oils.
You can easily try this method at home. All you need is paper and a candle. The specific candle you choose affects the work. Long wicks produce smooth patterns, while shorter ones produce darker and more opaque forms.
The resulting film is very soft and can by easily modified with the use of a variety of tools, such as brushes and feathers, and can even be integrated with other mediums such as gouache or oil paints. Just be certain to spray the drawing with a clear fixative when you're done, as the image is extremely easy to smudge.