"Hello, Tamblin," Dumbledore said pleasantly.
"The Patronus lessons haven't worked out; I've let Professor McGonagall know there's no use in proceeding."
"Don't be hasty, Tamblin. The Patronus charm is difficult magic. Many adult wizards are unable to produce a true Patronus."
"Even if I were able to produce a Patronus, which I don't think is possible, I very much doubt it'd be powerful enough to hold off all the Dementors in Azkaban. It has to be stealth, or nothing."
Dumbledore considered this. "I had hoped for you to have a back up, although I know your gift for stealth is formidable. I did have one thing I wanted to ask you in private, Tamblin."
Tamblin nodded.
"Why did you shelter Karkaroff? You surely knew the risk of it."
Tamblin frowned.
"You should ask someone about the risk of opposing the Death Eaters?"
"Forgive me, Tamblin, but I believe that you were raised to protect your family estates, to regard the continuation of that line as the utmost aspiration of your life. Sheltering Karkaroff was a terrible risk for you to take. I have to admit that I find it an odd action on your part unless you needed something from him." Dumbledore's blue eyes stared at him causing that slightly nauseous feeling Tamblin always felt at his close attention.
"I needed information. Something Karkaroff might have known."
Dumbledore looked both expectant and genuinely curious. Tamblin debated a moment but he saw no harm in telling the Headmaster now.
"My mother said something, during our unpleasant reunion, that suggested that my father may not have been Victhen Demosthene."
"And who would your father have been, Tamblin?"
Tamblin just stared until a look of deep sadness crossed Dumbledore's features.
"Oh, Tamblin. And what did Karkaroff tell you?"
"Nothing, I never managed to work up the nerve to ask him directly before…. But it doesn't matter- I've decided that Victhen was my father. My mother is deranged and I give her words no credence."
Silence lasted a while.
"When do you want me to go to Azkaban? With the Patronus issue out of the way I can leave soon if you like."
"I'm gratified by your earnestness in repaying the boon. This matter is of great importance, but it may be best to wait until Christmas break when your absence may not pique the interest of others."
"Just as well, there are a few contingency measures I should arrange."
Dumbledore nodded.