My favourite, bar none, is when the kids in the homemade costumes I don’t recognize at all roll up and say trick or treat, and I say “… you are?” And they take a deep breath, and you can _see_ them physically restraining themselves from dumping three hours of lore on you before they say “I’m this character from that anime”, and I know that I’m looking at the purest, undiluted kind of fan love.