Bellatrix had never been able to conceive a child of her own. Never felt the joy of a first kick or the instant love upon seeing a child open their eyes for the first time. A nephew was one thing, but not the real thing.
She had thought that a baby would bring some joy into a marriage that was built upon convenience and arrangement rather than love. Her House required heirs; it always had. She was the eldest of the sisters and the cousins at large. Her children, especially her sons, would be the patriarchs of the House once she was gone, and they would stand to inherit the lot of her father's hard work. But no children came. Year after year, disappointment after disappointment.
Rodolphus had tired of it. He had a brother with sons of his own, and the House of Lestrange did not stand to lose nearly as much as the Blacks did if no heirs came to pass. Narcissa had, of course, produced a son. The pride of Lucius and his father, and the gem in the eyes of his mother. Even Andromeda, the traitor ilk that had married the Mudblod Tonks, had produced a disgusting halfbreed daughter. Both of them had done what was expected in a manner of speaking, but Bella had, as her father reminded her whilst he was still alive, failed.
She had even turned to other men. Rodolphus refused to persist in their attempts, and so she thought hopefully another vessel would suffice. She would never tell to whom she had sought out and given her gifts to, the shame and betrayal would have cut too deep. She had done it nonetheless, and prayed that if the seed took root, the child's hair and eyes would be those of her own.
But none came. No pregnancy stuck or lasted more than a week or so. Again and again, she was tortured and driven half mad by loss and grief. The shame ate her alive, and for a long time, she had accepted that her life was doomed to be fruitless and lack honor and meaning.
Tom Riddle had approached her for the first time in her fifth year. Already then, his ideas and nature were intriguing and aligned with those of the ancient Houses. Strange, for a boy who was orphaned and of no royal blood, she had thought. They had less than a year to know one another then, because he had graduated that summer. Not until several years later had their paths crossed again, when he had gathered the ancient Houses to rouse their support. Rodolphus had known of his ancestry before that, but Bellatrix was enlightened to the return of Slytherin's heir for the first time that night.
What he offered in terms of riches and power mattered little to her. Her house was the most powerful, the oldest, and most respected. She did not need galleons or power, for she had it all already. It was the notion of a purpose that made her pledge her devotion of service and assistance to him, Tom Riddle, who was no longer a boy. He had secluded her, chosen her as his eire. He singled her out as the most powerful, rich, and respected member of the great Houses, and he was masterfully strategic in doing so.
He promised her a purpose that stretched beyond that of producing heirs. A means of making the agonizing pain of suffering alone end. She would join him in purifying the world, and give the children to come a world in which her and his legacy would never die. What was birthing children, compared to cleansing the world of those who would seek to harm her and her faith? What greater honor was there than to birth a new regime, ideology and rightful domination to the next generation?
In his eyes, voice, and power, she found the purpose she longed for. He would give her the world as her canvas. Would let her terror and trauma guide her freely, as she purged those who had made her weak, those who had betrayed her and oppressed her, and used their blood to paint the world as she saw fit. Why should they have the gifts and joys that she was denied? She was the ultimate warrior, the most powerful weapon, and the deadliest face.
"And when you bear my heir, and you will bear him, your fathers and their fathers will pale in your shadow."
That was what he had said, and he had sealed it with dark magic that grew and expanded in her mind every waking moment. Who other than him could promise her this? Who else to lead them than him? He who would give her everything, who let the inner rage and grief express itself through her carnage of those who opposed him. He was the prophet, she his apprentice. He was the end of the world, she was his sword. He was the Dark Lord, she the most loyal servant.