"How are you feeling Severus?" Albus Dumbledore said. He was stood at the doorway of Snape's office, looking in at his companion.
"The potion works," Severus said. "I can sleep peacefully on the floor during my transformation. But it does nothing to stop the pain."
Albus Dumbledore looked sad. "If there was anything I can do to spare you, Severus, but werewolves are very understudied. Wizardkind hasn't put much effort into developing a cure or relieving your symptoms."
"I know," Snape said, shortly.
Albus Dumbledore stared at Severus Snape. He had always been a rather moody and difficult person to get along with. Dumbledore liked him—he was a highly intelligent young man and the two often discussed various potion or transfiguration theories in their spare time—but he knew not many of the staff, bar McGonagall were overly friendly with him. Snape and McGonagall had a friendly rivalry over Quidditch, which they both enjoyed.
"I tried to change things, you know," Dumbledore said, finally. He tended to keep things close to his chest. Secrets and lies—that was Albus Dumbledore. But something prompted him to tell Severus the truth about what had happened—perhaps it was a wish for the potions master to not blame Dudley Dursley and his friends for what had happened.
'Change what?" Snape had been drinking a goblet of water, but he paused, eying Dumbledore shrewdly.
Dumbledore took a deep breath and told Severus all about the time turner. Snape's face paled.
"That was beyond reckless!" Snape snapped, once he had finished. "Do you realise the danger you put them in?"
"It was a calculated risk," Dumbledore said. "I knew … I thought the risk were minimal. I hoped Mr. Dursley and Miss. Granger would be able to change things. But alas …"
"You sent two 13-year old's back in time!" Snape said through gritted teeth. "And to what, spare Black from being kissed?"
"To spare you from your fate," Dumbledore said.
"I'm not worth the risk. They could have died. Who knew what would have happened?"
"It was a calculated risk …"
"That had no chance of working!" Snape almost shouted. "You gambled it all on some gambit that had a fraction of a chance of succeeding."
"I see now it would have happened anyway," Dumbledore acknowledged. "I believe no matter what Mr. Dursley's actions would have been, events would have played out as they did. Time … it is a mystery beyond us all."
Snape still looked angry. "Why?" he demanded. 'Why risk so much?"
"Numerus reasons," said Dumbledore. He stared at Snape. "I need you right by Voldemort's side. You being a werewolf makes that task so much harder given his prejudices."
"I also wished to interrogate Sirius Black …"
"Black is a murderer! He tried to kill me at Hogwarts. He betrayed the Potters. He murdered 13 people. What is there to interrogate?" Snape demanded.
"There are many holes in the story about Sirius Black," Dumbledore said softly. "I would have liked to have gotten to the truth. "Why did he betray his best friend? When did he decide to? Why did he escape? Why was he so desperate to get into Gryffindor tower? There is so much we don't know Severus, and so much we will never know."