Lord Sirius Black walked towards Dumbledore's office after getting the password from a surprised Professor Flitwick. He saw the gargoyle jump to the side, so he stepped onto the moving staircase and knocked on the door. When he heard the old man invite him in, he opened the door and stepped inside.
The room was exactly as Sirius remembered it, with Dumbledore sitting behind the ornate desk, on a throne-like chair. He seemed surprised to see Sirius there.
"Sirius?" asked Dumbledore, confused. "I believe I asked Harry to meet me before he leaves. What are you doing here?"
"I'm here because I am his guardian and this does not concern his schooling," said Sirius curtly as he took a seat uninvited. "What is this about? Wait, let me guess… Is this about making Harry go back to Petunia?" he sneered.
Dumbledore mentally sighed. He did not expect Sirius to come here himself. He thought he might be able to persuade Harry by bribing the boy with books from his personal library, but he didn't think it would work with the Lord of House Black sitting in front of him.
"Sirius, you have to see reason. The protection I had created around the Dursley residence was based on Lily's sacrifice. As long as Harry calls the place home, and where Lily's blood lives through Harry and her sister, Voldemort cannot touch him. It is imperative that he goes back there for his own protection."
"I will never allow that, Dumbledore," said Sirius coldly. "You're delusional if you think I would condemn Harry to such suffering again. You knew Petunia was a bitch. Lily told you so, didn't she? And yet you placed Harry with that woman and her husband, making my godson grow up in a magic-hating, abusive household. I can't believe you would sink so low as to condone child abuse!"
"Sirius, I had no idea -"
"Save it!" spat Sirius angrily. "You should have known about it since it was you who left him there in the first place. You were the boy's magical guardian. It was your duty to protect him! I don't even want to know what state my godson would have been in if he hadn't escaped when he had. There are a lot of mysteries surrounding you, Dumbledore and I don't like it. You're playing a very dangerous game. It's rather convenient that it was you who sealed James' will which stated that I was innocent. It was convenient that I didn't know who actually cast the Fidelius Charm. All this time, I was under the impression that it was Lily until Harry proved otherwise. You're very lucky that James and Lily's journals are not admissible in court as evidence because if I had solid proof of your involvement, I would have ensured that something was done about it. You sent me to Azkaban on purpose. You put Harry with Petunia for a reason. I'm warning you now, Dumbledore. Stay out of my way and out of my son's life."
" Your son, Sirius?"
Sirius fixed Dumbledore with a haughty look. "He's as good as my own. I couldn't love him more if he actually were my son. I repeat; leave Harry alone or you will face my wrath!"
With that, Sirius Black got to his feet and walked out of the office, slamming the door in the process, leaving Dumbledore to ponder the situation. The headmaster's eyes grew hard and a frown formed on his face. He seemed to be the recipient of many threats lately. He had to get things back under control; get Harry under control. Sirius was, unfortunately, protected. The Chief Warlock could wage political battles, but that was it. He needed the young Lord Black for the fight with Voldemort when the Dark Lord eventually returned, and hence, didn't want to consider any route that could sour their relationship further.
Dumbledore turned to his trusted phoenix. "We need to find him, Fawkes," he said softly. "I think it is time we brought him back."
The phoenix trilled and soon, both the old headmaster and the phoenix disappeared in a flash of flame.