constellations inked in blood
The youngest generation of the Ancient and Most Noble House of Black is rather close in age (or, really, they mathematically should be).
There are the sisters: angelic Narcissa, sensible Andromeda, and loyal Bellatrix, and of course, the brothers, the wild Heir and the dutiful Spare: Sirius and Regulus—all five bound together by shared nursery promises and blood.
Yet, Sirius still is sorted into Gryffindor, Andromeda still runs off with a muggleborn, Bellatrix still begins to lose her mind, Narcissa still does as she is told, and Regulus… Regulus still joins the Dark Lord.
He still goes to the cave.
He doesn’t leave alone.
TLDR: how The Black Family embodies the Big, Screwed-Up Family Trope. “though if you piss off one of them, the rest will instantly band together to destroy you in order to uphold the Family Honor.”
[AU of the First Wizarding War in which a Horcrux muddles the conception of Toujours Pur and The Family, dysfunctional though it may be, finds a third side in the war.
Or: blood purity is *as* important as the near death of their children to the Elder Generation of the House of Black.]