a) I have two characters without a plot
b) I have a line without characters or a plot going round and round in my head, driving me completely barmy!
As for a) I have a thirty year old Harry and Draco wandering around in my head without a plot. They have back story, they have current relationships with other characters, but they have no plot. Harry has long hair, an eye patch that covers the fact that to wizards his left eye looks like a carbon copy of Voldemort's red ones and can only see magical things, and to Muggles it's just a black hole. He's rather partial to black clothes. Draco also has long hair, a liking for leather and has light sensitive eyes thanks to an accident with a fire-crab. They have been away from England for twelve years since the final battle with Voldemort, acting as independent magical creature retrievers for the last ten in which line of work they are known as H and D; they are married, and they have only returned because something bad is going to happen. Do I have a clue what the something bad is? Not likely, that would mean I could write an outline and they'd shut up.
Then there's the line going round and round in my head: "Harry, love, what are you doing?" Do I know who says it? What it's about? Why someone might be making that enquiry? Nope - not a clue, and it's driving me nuts (okay, more nuts :)). Stupid bloody brain!