the_debt_of_time

"I was supposed to see you alone, Potter," Snape ground out, "but Black―"
"I'm his godfather. I've a right to be here."
"I am here on Dumbledore's orders."
"You need my permission."
"By all means stay, Black. I know you like to feel... involved. Tell the boy what
the headmaster wants. You are very good at... sharing."
Sirius's eyes widened, and the image of himself in the orchards with Remus and Mia
came quickly to mind. "What the hell is that supposed to mean?" he growled, letting his
chair fall back down on all four legs with a loud bang.
Snape sneered maliciously at him. "Merely that I am sure you must feel frustrated
by the fact that you can do nothing useful," he said, putting a delicate stress on the word,
"for the Order."
Sirius looked back down at the table as he tried to rein in his temper, something
that Harry had already seen too much of in the short time they had spent together. Sirius
did not want his godson to think poorly of him, but it was hard to ignore the fact that
Snape had witnessed one of Sirius's most sacred and intimate memories to date. Something
that had not even been spoken of—in detail—to James, who had actually been a part of
the pack.
When Sirius said nothing, unable to speak without screaming, Snape took the cue
to continue. "The headmaster has sent me to tell you, Potter, that it is his wish for you to
study Occlumency this term."
"Study what?" Harry asked.
"Occlumency, Potter. The magical defence of the mind against external penetration.
An obscure branch of magic, but a highly useful one."
"Why do I have to study Occlu... thing?" Harry blurted out.
"Because the headmaster thinks it a good idea," Snape responded. "You will receive
private lessons once a week, but you will not tell anybody what you are doing, least of all
Dolores Umbridge. You understand?"
"Yes. Who's going to be teaching me?"
Snape raised an eyebrow. "I am."
Sirius felt Harry's panic and glanced up to see terrified green eyes staring at him,
pleading for help. He winced at the sight, feeling so incredibly inadequate. "Why can't