Monomania is a common theme in particularly creepy horror stories. It's where a character focuses all of their attention on one thing to a bizarre extent. Sort of like The Tell Tale Heart by Poe.
So here's the question: what would be a creepy thing for someone to focus on?
Name:
Anonymous2010-05-18 11:15
How about a dead pet. He keeps it stuffed and takes it everywhere with him- even on dates!
"There are no limits to the possibilities of monomania," I
answered. "There is the condition which the modern French
psychologists have called the 'idee fixe,' which may be trifling in
character, and accompanied by complete sanity in every other
way. A man who had read deeply about Napoleon, or who had
possibly received some hereditary family injury through the great
war, might conceivably form such an idee fixe and under its
influence be capable of any fantastic outrage."