His father had been surprisingly civil and agreeable. He had even suggested having someone on the other side of the war would help reduce the risk that the House would be decimated – after all, if the Light won then hopefully Sirius would be alive to continue the line. Sirius had politely agreed and privately thought he would never be the Head of House despite his father spending years grooming him to be just that; that he would never want to be the Head of House.
The irony was bitter to swallow, Sirius thought with dry amusement. Old history, Sirius told himself briskly. He might never have intended returning but he was there for Harry. He just had to remember that and all else was tolerable.
He sat down in his father's chair – his chair. He ate one of the waiting sandwiches as he reached down and rummaged in the top right drawer. He drew out a selection of wands; his father's, his mother's and his great-grandfather's. He tested each as he finished the make-shift meal and drank the accompanying juice and water. He settled on his great-grandfather's wand of oak with a core of dragon scale. It was an acceptable match and would suffice until his name was cleared and he could replace it.
Sirius pulled out a small ritual bowl and dagger from the bottom drawer. "Familius magicus." He tapped the bowl with his wand making the inside cloud up with swirling silver sparkles of magic. He slashed his palm without ceremony and let the blood drip into the bowl.
"I, Sirius Orion Black, claim by blood, by law, by magic, the House of Black. I swear to lead it with honour and fairness; to protect and shelter those who belong or ally to the House of Black by blood, by law, by magic, by oath; to deliver justice on those who break oath and trust with the House of Black. So have I sworn; so mote it be."
The magic surged out of the bowl and surrounded him; a bright cascading stream of silver that blanketed his core and tested his worthiness. He could barely breathe under the power of it; magic steeped in blood and ritual; magic as black as his name. But he refused to bow to it; he was a Black and the magic was his to command not the other way around. The magic left abruptly and settled before him in the cloudy shape of the house totem: a silver hooded snake. It bowed to him solemnly and disappeared.
It had worked.
Sirius let out a shaky breath and pushed his hand through his wild hair. The strands tangled unexpectedly with a ring on his finger and he drew his hand down to stare at the Lordship ring; a black onyx stone stamped with a silver snake set in a platinum band. The ring had been called to his finger with the ritual. He'd worn the matching Heir ring once upon a time and as his eyes fell to the desk he saw it sitting in the bowl. He gave a sigh, picked up the Heir ring and secured it in the wooden box on his father's desk where the ring had traditionally been kept. A tap of his wand had the box locked and only he would be able to open it.
He got up and turned to the fireplace with its surround and mantel of stone. In the centre of the mantelpiece the Black crest was carved in wondrous detail; it was also the keystone for the wards. Sirius pressed his still bloodied left palm onto it. He felt the wards shift to his control.
"Fidelius." Sirius said firmly. He felt the wards respond and knew his location was hidden completely with satisfaction. "I, Sirius Orion Black, am named Secret Keeper." He focused again and shut down the floos with a thought; the portraits were put to sleep to prevent them from spying.
He sat back down, exhausted. There wasn't much time left before the end of school and there were a hundred things he had to do in order to ensure Harry would be away from the Dursleys sooner rather than later, but in truth all he wanted at that moment was a bed.
Kreacher popped in beside him. He held out a folded piece of parchment and another ornate box. He looked nervous. "Young Master Regulus ordered Kreacher to give these to you but Mistress punished Kreacher when Kreacher told her of young Master Regulus's death and ordered him to stay in the house."
Sirius took them with a frown.
"Lord Black's bedroom and bathroom are ready when you wish to retire." Kreacher popped away again.
Sirius looked down at the box and parchment. He sighed and set the box on the desk, opening the parchment.
"Dear Brother,
I regret many things but mostly I regret listening to our Mother and not following your path. I broke faith in the House of Black by taking the Mark of Voldemort, someone who I have realised is totally without honour; someone who would prefer to rule us all. He kills without regard for blood or for allegiance. I have seen pureblood wizards in his service fall at his hand and I have seen enough of the horrors he perpetrates to know I regret my decision to follow him.
I write this with the knowledge that I go to betray him tonight. It is this mission I must tell you about; he created Horcruxes. He has used items of great value to do so believing they will not be destroyed. He gave Hufflepuff's Cup to Bella for safe-keeping, a diary or journal of some sort to Lucius and the location of Slytherin's locket to me. I do not believe these are the only ones – he prefers seven as a number in rituals so with the assumption the seventh fragment remains in his mortal body or on the mortal plane, there will be three others. He spoke of an old Head of House ring which I fear may be a fourth, and I believe another item of Ravenclaw's resides at Hogwarts but as he only made an allusion, I could be wrong. That leaves one unaccounted for, brother. (I know you have problems with basic arithmetic). These abominations will need to be destroyed before he can be defeated outright.