Writing Prompt - fog

It is a foggy morning, with a murky gray fog holding close to the trees, so how about a writing prompt pertaining to fog? Write something that has your character in a dense fog, maybe evading someone or looking for someone (something?). A traveler that got lost in the fog? Is the fog natural or caused by some artificial means? Can the character see through it reasonably well or is it the sort of fog that obscures even their own feet? If you're a horror, fantasy or sci-fi writer - is the fog itself somehow alive?