Sirius Orion Black is the last of the male line, and Grimmauld Place Number Twelve is his tomb.
It is his home as well, but that’s neither here nor there. Not for Sirius, who sees further than Number Twelve’s façade: he is its Master, was born in the mistress’ bedroom, learnt to crawl and walk and run in its hallways and learnt to whisper and speak and scream through its doorways. Master learnt to read and write in the study its previous Master stayed in until his death, learnt to sit up straight and hold cutlery in the dining room that ends up abandoned, learnt to swallow his emotions down down down like his father before him and his father before him with a parent looming over his tiny human body.
It’s always been this way. Number Twelve knows no better than how his Masters of the Past and Present have been raised, have grown, have pushed their power into the tough-cold-living stone of its cellars. Number Twelve has belonged to the House of Black since before it was built, before it rose up from pre-existing foundations permeated with old magic. It has belonged to the family for generations, and in this day and age, its current Master shall be its last.
Number Twelve shall listen to him. Number Twelve was built to listen, to accomodate, to warp and change to the wishes and whims of its Master. It became a fortress because its previous Master wanted it to, strengthened the wards he weaved by borrowing his willpower—softened its floors when children fell because Master-of-the-Past did not like cries of pain, bore down on unwanted guests because Master-of-the-Past did not like most people. Number Twelve listens and follows both spoken and unspoken orders. That is what it was built for.
Number Twelve is not just a neglected, abandoned family home. It is not dilapidated and haunted just because it was left to rot for so many years, just because its only inhabitant for nearly a decade was an old elf influenced by an object emanating magic fouler than any kind Number Twelve has ever housed; it is because its current master is unable to imagine it any differently, and Number Twelve adapts accordingly, because Number Twelve listens.
Master is the last bearing his last name, the last of the male line, and the House of Black is forgotten glory. It is a family that has sunken down from their presumed superior position like a rock hurled into deep waters. How else would this decline present, than decaying walls and festering infestations of vermin? Number Twelve is Master’s prison and it morphs itself into one, turns its air oppressive and its temperature down low, narrows its winding corridors and shrouds itself in misery.
Number Twelve becomes the representation of Master’s biological family, gone and dead-won’t-stay-dead, because Master sees Number Twelve as such. Ghosts creep behind ratty curtains and loom in shadowed corners, become mirages by moonlight and play in the motes of dust, and Number Twelve lets them because this is what Master thinks, what Master says. When Master’s mood drops, so does Number Twelve’s, because when Master is saddened and angered he thinks, deep down, that these other residents ought to be uncomfortable and irritable as well. When Master’s mood becomes cheerful, Number Twelve dutifully pushes the joy into its floorboards and walls, as Master wishes to share his happiness and Number Twelve gladly helps. Number Twelve locks doors when Master does not want to see the residents who are filling Number Twelve with life and Number Twelve changes its layout when Master does not want to be found. Number Twelve was built to listen to and follow orders, and it will do that until it falls apart. What Master wants, Master gets.
Number Twelve does not appreciate the other residents when they upset Master. Number Twelve does appreciate the other residents’ attempts to clean its rooms, wishes it could show how grand and beautiful it used to be and can be. But Master thinks cleaning to be a lost cause, so Number Twelve ensures it is a lost cause: it presses dust out of the smallest corners without any trouble, and it delights in Master’s delight when the other residents feed their frustration into its walls.
Number Twelve listens and acts. Master refuses to look in mirrors lest he see something he does not want to, so Number Twelve darkens them, dirties them, ruins them until they cannot be fixed. Master believes and does not want to be disproven about the hatefulness of the elf, so Number Twelve does not even attempt to improve the relationship. The elf was the one to bring the foul and dirty object through the very wards Master-of-the-Past erected to keep such magic out anyway, and Number Twelve is old enough, fed enough, to hold a grudge. Master’s joy, even if it is tainted by grief and ire, is Number Twelve’s joy. Number Twelve is, after all, simply glad to have a Master.
It has always been this way, even if it is different now, with a Master so similar yet so different to Master-of-the-Past. A fortress and a tomb are synonyms in the loosest definition, and Grimmauld Place Number Twelve now has a Master who sees it as his tomb: as Number Twelve cannot begrudge its Master anything, it will be a tomb. But Master sees it as his home too, deep down, and Number Twelve was built to be a home.
It will adapt accordingly.