A/N: My own ideas about what Sirius might have been feeling or thinking when he was locked in Flitwick's office in PoA. Enjoy!
Sirius woke up slowly. The last thing he could remember was chasing Peter into a group of Dementors. He shuddered at the thought. There must have been a hundred of them! The Animagus knew that he must have passed out when confronted with all those Dementors.
But then, why was he here?
He slowly opened his eyes and tried to get up. It was then that he realized that he couldn't move. He was bound and gagged, with the same charm Snape had used on Remus in the Shrieking Shack.
Sirius lay back down, fighting the sick feeling of horror that threatened to engulf him. He looked around at the room he was in. It was probably an office of some sort; there was carpeting, a desk, and some chairs. Judging by the moonlight coming through the big, mullioned windows, he had been unconscious for maybe half an hour to forty-five minutes.
He lay there, struggling against both his bonds and his feeling of panic. Sirius felt terrified. At best, he would be put back in Azkaban. At worst…he didn't even want to think about that. The Animagus felt a chill of terror at the thought of what the Dementors of Azkaban might do to him.
After perhaps ten minutes, Sirius heard voices in the corridor outside the office he was locked in. Sirius's stomach clenched. If that was the Dementors…he shuddered. He felt so vulnerable lying on the ground, tied up.
The voices got closer to the door, and Sirius could tell that it was Dumbeldore talking to Fudge.
"For Merlin's sake, he's a murderer, Dumbeldore! He already put Potter, Weasley, and Granger under a Confundus Charm, a true miracle he didn't do anything worse to them. Think what he might do to you! Besides, you know as well as I do that Black will tell any lie to save himself."
"I have told you this before, Minister. I wish to hear Sirius Black's side of the story."
"Oh, very well," Fudge huffed. "Be quick then, Dumbeldore. The Dementors are due to arrive soon."
"Very well."
The door opened, and Sirius saw Albus Dumbeldore enter the room. He walked over to Sirius and gently untied the ropes that bound him. Sirius sat up, rubbing his wrists where the tight cords had cut into his skin.
"You don't believe that I killed Peter and those Muggles, do you Professor?"
The sapphire eyes behind the half-moon glasses were grave. "No. I do not believe that you betrayed Lily and James, or that you killed Peter Pettigrew. I would, however, like to hear your side of the story."
"What do you want to know?"
"Everything."
For the next quarter of an hour, Sirius spoke. He told Dumbeldore about how he and his friends had become Anamagi, about how he had convinced James and Lily to change to Peter as Secret Keeper, how Peter had betrayed them, killed the Muggles, faked his own death, and framed Sirius, about how he had escaped from Azkaban and slipped into the Hogwarts grounds, how he had been helped by Crookshanks to find Peter, and how he had found Harry and his friends and managed to convince them of the truth.
"But what am I going to do?" Sirius asked after he had finished "No one else will believe me without Peter, and if no one believes me…"
Dumbeldore looked gravely into the young man's face. Sirius's eyes, which had once been a deep, sapphire blue, had been reduced to a dull, lifeless gray by his long years in Azkaban. Dumbeldore had known Sirius Black very well when he had been at Hogwarts, and the Headmaster could see how much Azkaban had changed him.
He sighed. "I cannot override the decision of the Minister of Magic. I cannot do anything to help you." Dumbeldore turned to go. At the door, he turned back to Sirius. "Watch the window." With that cryptic message, Albus Dumbeldore, the most powerful wizard of the age, left, relocking the door behind him.
In Sirius's eyes there was a blank, empty despair. If Dumbeldore would not, could not, help him, he was doomed. He fought back a scream of rage. Watch the window! What kind of advice was that? Watch the window! He was going to be worse than dead, and no one was going to help him. Sirius strode over to one of the chairs and sank into it, his face in his hands. He was going to be worse than dead. That was it then. He was as good as dead. He thought back to his first week in Azkaban.
Sirius leaned back against the stone wall of the cell, feeling the chill of the stone through his robes. The sudden clang of metal on stone reached his ears.
Looking out through the iron grill door to the cell, he could see two Dementors near a cell on the opposite wall. Curious as to what they were doing, Sirius leaned forward. One of the Dementors had grabbed the struggling man and was pulling him forward. The other Dementor had lowered its hood. Sirius knew now what they were doing. He wanted desperately to look away, but found that his eyes were locked on the grisly scene. He watched with a horrified fascination as the Dementor with the lowered hood held the man with its rotting, clammy hands.
The man, knowing what was coming, was struggling with all his might. Heedless of the prisoner's vain attempts to get away, the Dementor with the lowered hood leaned down, putting its gaping, shapeless mouth close to the man's face. Latching its jaws onto the man's, the Dementor sucked hungrily. Sirius could see the man stop struggling and lose interest in what went on around him. After a minute, when the Dementor stood back up, the man sank down to the floor of the cell, a terrible, blank look in his eyes.
The man lay there for a few hours before a Hit Wizard came.
"Get up." the wizard commanded sharply. The prisoner who had had the Dementor's Kiss performed on him stood listlessly and followed the wizard down the hall. Sirius watched with terrified eyes.
Sirius did not want that to happen to him. He thought of those terrifyingly blank eyes, empty of all emotion and thoughts, and shivered.
That must be what Muggles call zombies, he thought, to have the Dementor's Kiss performed on you and have no will of your own.
He sat with his head in his hands, a kind of blank despair coursing through him. He would forget all his memories of his friends; every good time they had had together and every special occasion they had celebrated would be lost forever. He wouldn't even be Sirius Black anymore.
So this was where it ended. This was where all his life ended.
As he sat there, feeling nothing but despair, he heard a tap on the window. Looking up, he saw the hippogriff that had been tethered in Hagrid's yard hovering in front of the window. And there, riding it, was Harry and his friend Hermione!
His jaw dropped. What were they doing here? He rushed to the window, but it was firmly locked, and he didn't have a wand to open it.
"Stand back!" Hermione called to him, her voice faintly muffled by the thick glass. Clutching the back of Harry's robes, she pulled out her wand and performed a charm. The window sprang open.
"How…" Sirius asked weakly, still staring at the hippogriff and the two teenagers riding it.
"Get on. There's not much time." Harry panted, trying to hold the hippogriff steady. "You have to get out of here now! The Dementors are coming—Macnair went to get them."
Sirius scrambled out of the room and onto the flapping hippogriff, trying hard not to think of the seven stories to fall if he slipped.
Once he had clambered onto the airborne hippogriff just behind Hermione, Harry shook the reins, and the hippogriff soared straight up.
There was a rush of cold, bitter wind as they flew. Sirius laughed out loud, delighted to be flying again after so many long years. He hadn't felt this alive, or this truly free, since he had first escaped Azkaban.
After a brief moment of flight, Buckbeak landed heavily on the thick stone battlements of the castle roof. All three riders turned and slipped off the sleek back.
"Sirius, you better go, quick!" Harry said. "They'll reach the office at any moment, they'll find out you're gone…"
Sirius had to know how Ron was. Would he be OK? Sirius still felt rather guilty about the bite.
"What happened to the other boy, Ron?" he asked.
"He'll be OK. He's still out of it, but he'll be fine. Go, quick!"
Sirius, however, made no move to leave. Looking at the two frantic teenagers, he realized that he owed his life to them. If they hadn't gotten him out, he would be worse than dead.
"How can I ever thank—"
"GO!" Both Harry Hermione shouted. Realizing that they were probably right, that he should be leaving soon, Sirius turned Buckbeak.
"We will see each other again." he said to both. Then, turning to Harry, "You are truly your father's son Harry."
Sirius remounted the hippogriff and squeezed Buckbeak's sides with his heels. The enormous wings flapped, and the hippogriff took off into the air.
Looking back, Sirius could see the two teenage wizards watching him. He gazed at them as long as could, but a cloud drifted in front of him, and they were gone. He instead turned his attention to what lay ahead.
He and Buckbeak were flying through thick cloudbank. In a moment though, they burst through the layer of cloud and were flying through the moonlit night above the cloud cover. Buckbeak skimmed the top of the clouds before soaring up to fly in the clear, star speckled night.
Sirius laughed, ecstatic both to be free and to be flying. He hadn't flown in years. He leaned in close to the hippogriff's neck, sensing that the giant beast was joying the flight as much as he was. Sirius breathed deeply. The air was sharp and cool. He finally felt that he was truly free. The feeling of it was wonderful, the most wonderful he had ever known, even better than escaping Azkaban.
After enjoying the sensation for a few more minutes, Sirius stopped Buckbeak to get his bearings. After a few minutes of calculating, he realized that he had been flying northeast. He wanted to be going south. He turned Buckbeak to the right direction and, as the hippogriff winged its way steadily south, he thought of what lay ahead.
The road ahead would be difficult and dangerous, Sirius was sure of that. At the moment though, it didn't bother him too much. He had escaped impossible situations before; he would be able to do so again. He could handle whatever happened to him. The way would not be easy, but he now that Moony and Harry believed him, he knew he could handle anything the world threw at him.