Author's Note: I don't own the Potterverse it is the exclusive property of JK Rowling.
This short story takes place during the summer following the fall of Voldemort. I wonder if Narcissa knew that it was Bellatrix who killed Tonks.
Narcissa in Mourning
Narcissa Malfoy glanced over the cook book again. Since Lucius had unintentionally freed Dobby from servitude five years previously, she had had to learn how to prepare meals by magic. It had actually become something of a hobby of hers to attempt the more elaborate recipes. In recent months it had been a welcome distraction from the ordeal of their terrible house guest...
She reflected on the events of the beginning of May. She had helped save her son, but had lost her sister... and a niece she had never known. Andromeda's child. She blinked and shook her head. She had never spoken to the girl... all because of some absurd quarrel with her sister that she had had no real desire for. She shuddered at the memory of Voldemort urging Bellatrix to kill her own niece. Voldemort had been burned and his ashes cast into the sea. No one would mourn him. But there had been the terrible prospect before all the survivors of burying all the other dead that had included their relatives and their friends...
Narcissa had visited the graves of both her sister and her niece. A tear rolled down her cheek as she reminisced. From the grave of Nymphadora Tonks there now grew a rose that had been pink, but had turned violet when she had paid a short visit the previous week. From Bellatrix there grew a briar. Narcissa had taken a cutting from each and was growing them together in her flowerbed. The rose now grew round the briar.