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.
Tonight, I will retrieve the locket. I hope I return and tell you about this letter in person when I present the locket and my knowledge to you and ask for protection. If I don't return, Kreacher has orders to give this and hopefully the locket to you. I hope it helps the Light – more importantly, I hope it helps you.
I have not been the best brother, Sirius, but I go tonight hoping to restore my honour and do you proud.
Regulus"
The letter crumpled in his hand. Sirius closed his eyes, remembering his brother. Sirius had protected him from their mother all their childhood but the year Sirius had gone to Hogwarts had been enough for her to turn Regulus against him. He sighed deeply, swamped with his own regret that Regulus hadn't lived to tell him in person that he'd seen the light – literally.
But…bloody hell: horcruxes!
That was how Voldemort would rise again. And when he did, he'd come after Harry, Sirius was certain of it.
It was just too much to think about after the day and night he'd had – finally having a chance to talk with Harry, facing Peter, reconciling with Moony, having to charge down Moony to save the kids, having Harry save him from the Dementors, having Harry save him from being Kissed, escaping, claiming the House of Black and setting the Fidelius charm.
Tomorrow; he'd deal with it tomorrow, Sirius decided, locking up the box Kreacher had left – the one which presumably contained the locket with its fragment of Voldemort's soul – in the desk.
He went in search of his bed.