"Come in, Severus!" Dumbledore stood with his back to the door adjusting the position of some figures on a table. The Potions Master stepped forward and scowled as he took in the flow chart of roles, places, and events covering the very large table. The surface glowed with magic and in a corner a parchment blurred and then formed the numbers "999,978 to 1" as Dumbledore took his hand away.
Snape swallowed a curse and growled, "Plotomancy is dangerous, Albus. Look too hard at a path and it will crumble. Do you want us to be left with a series of desperate coincidences and errors as our only path to victory?"
"The power of narrative is our best weapon, Severus. If we prepare too well, act too logically, then this will become You-Know-Who's story and he shall win. We must increase the tension, overcome the obstacles rather than by-pass them. Only if the odds are a million to one can we be certain of success!"
"Just because Whatisname got blown up by a freak improbability last time doesn't mean you can count on that working again. Being lucky once doesn't mean you should count on being lucky the next time. You didn't rely on luck with Grindelwald."
"No, but he moved openly, and we could bring the power of the wizarding nation to bear against him. Life was harder then and people were prepared to do hard things. Now we live softly on our Muggle-made sheets and pillows and very few will endure the suffering to win a war. Easier to deny the threat and live in comfort. We must have a plan that needs only a handful of abused and despised children to serve as our foot soldiers. They can win through against million-to-one odds."
"And will you be asking those children to volunteer for all this suffering and death, Headmaster?"
"Of course I will, Severus. What do you think the traditions of House Gryffindor are for if not to produce brave volunteers for whatever cause I espouse?"
"Merlin's Spotted Dick, Albus! Do you care nothing for them?"
"I care for them, Severus. As much as I care for each one of the other children who will sleep peacefully because of the sacrifice of those few." He moved the "Explain Horcruxes" marker closer to the end of the table and the parchment reformed at "1,000,011 to 1." Ignoring Snape's sneer he straightened and said, "That's better. Pity I can't find other places to fit that one. Have to add another deus ex machina . . . hand me that little sword in a pond from the end table, would you?"