I was laying on the ground and Flitwick was talking to someone who I recognised as Albus Percival Wulfric Brian Dumbledore
also known as headmaster of Hogwarts school of witchcraft and wizardry.
Also known as one of the most powerful wizards in magical Britain famous for his defeat of dark load Gellert Grindelwald and the only person Voldemort feared.
"Of course, Headmaster," I heard Flitwick say from somewhere below me. It's been more than a decade since Sirius had listened to Flitwick speak but it was easy to recognize his voice since it was so unique. As Flitwick was taking the stairs, I tried to move my body to get into a more comfortable position but I realized I could neither move any part of my body nor speak anything. I didn't even notice when Flitwick petrified me, he must have done it at the same time that he took me from Snape. 'Well, he is the charms professor for a reason, I guess ' I thought to myself. It was silent for a few minutes with only the sound of his feet echoing across the hallway before I heard him stop. We must have reached his office because I heard him say something in the goblin language. That must have been the password to his office because I heard the door open the second he said that. Flitwick floated me inside his office before he moved and opened another door. I hear him mutter a spell that seemed to be a variation of the Accio spell and heard some things rushing through the air, it was a few minutes later that I felt myself being moved into the room. I was gently deposited on the floor and as I heard the door click shut I realized that I could move again. I opened my eyes slowly and a bare room came into my view, it was a small room that seemed to have been used as storage.
At this moment all I could think was that I am very proud of my godson to be able to produce a corporeal Patronus at the age of thirteen. I should not feel that much pride After all I never even met harry before today but I guess some part of Sirius is still alive and we have been merged. After a few minutes, Dumbledore came and unpetrified me.
I was avoiding looking at his eyes as naturally as possible keeping my eyes low enough to see only his beard like I was grieving.
"Sirius, how have you been," Dumbledore asked calmly without a note of hostility in his tone.
"I am fine dumbledore," I said without moving. We sat there for a while and the atmosphere was getting a bit weird so I continued "except for the part where I am in the storage room right now ".
"I remember you being above the world in your sixth year when pooter's officially adopted you after you ran away from your home" Dumbledore continued "what happened in your life that made you betray your best friend Sirius"
I chuckled bitterly "what made you think I betrayed them, Albus?"
"I clearly remember casting the Fidellius charm and you becoming their secret keeper and only you can give up the location of potters to Voldemort"
"Yes, but they changed the secret keeper to Peter last moment."
"Why would they do that?"
"Because I told them to…" I said gritting my teeth "I was nearly captured at a time by Bellatrix who kept me alive so I can tell the secret to Voldemort. On that day I found out that being a secret keeper is an open secret and everybody will target me so I thought of a "brilliant" plan to change secret keeper to peter without telling anyone other than us four (James, Lily, Peter, me). I barely escaped that time and I understand the need for a decoy. I was afraid that if I get captured James and Lily won't be safe so I removed myself as a secret keeper but keep the ruse up so that even if I get captured, I can't share the secret.
Dumbledore looks shaken and says "I can't convince Cornelius to give you a fair audience but ill see what I can do about your escape.
Then he takes off and I was alone in the cell.