Here is a quick little one-shot featuring lovely Bellatrix Lestrange. I wish her character was expanded on more, so I've done that for myself now.
Enjoy!
Bellatrix Lestrange was one of the most frightening Death Eaters of all time. With hair so dark it seemed nearly indigo and heavy lidded eyes like a crow's, she was other worldly, horrifying, and so seductively dangerous that one couldn't help but find her beautiful. She was the queen of darkness, and carried herself as such. Granted, her madness had swallowed her deteriorating brain whole during her time in Azkaban. Her regal corpse turned to a grimace of what it had once been. What her broken mind lacked in subtlety, however, she made up for in pure brutality - the Dark Lord made sure of that.
I blame him, mostly, for the state of my sister by the time she died. Cruel though she was, she had a breakable quality about her. Her porcelain skin seemed to crack during those final few months. I don't mean to excuse her behaviour during that time, Hermione, dear. But her actions broke her mind and what was left of her heart, in the quiet of her room at night. Her moments of insanity destroyed her, not that the Dark Lord ever saw that. To him she was a machine - willing to kill and torture at a moment's notice. The woman I knew was very different.
We were young when we fell into Tom's thrall. She was newly married, as was I. We had lost our sister. Bella was always closer to Andy than she was to me. That was the beginning of the end, I think. She stopped talking as much. The bright eyed girl I had known at Hogwarts faded into the princess she had become, she found solace in the dark arts, and I found I could not fault her for it - though I tried, truly, I did.
She could not have children of her own. We learned that early on in her marriage. The Dark Lord had sneered at my sister's pain. After all, what good is a pureblood bitch if she couldn't populate the wizarding world? So Bella made herself necessary. She embraced her agony and rage. She became it.
When I gave birth to Draco, it very nearly killed me. My body was not equipped for the strain. But Bella doted on him as much as I did. He was her joy. It was Bella who taught him how to fly his children's broom and bought him his first potion kit. She was far more present in his early life than either Lucius or I were, I'm afraid. Draco was the child she knew she could never have. And still the Dark Lord would send her on missions; each one worse than the last.
She was cruel, I will not deny that. But unlike her husband and brother in law, she was loath to hurt a child. Even muggle children, she held them in her arms while other Death Eaters tortured and killed their parents. She soothed them, hid their eyes from terror. She never wanted them to die in fear. And when their turn came, she was quick. Brutal, yes. But quick. If she was told that all of the family had to die, she took each child's death as her own burden, her own task. Each death weighed on her but she did it. Because she wanted to stay important. And she was praised for it, her brutality and darkness. The praise did not soothe her guilt.
Around that time, she became addicted to Dreamless Sleep. I was not surprised. It was potions or night terrors, I understood her addiction.
And then the Dark Lord spoke of a prophecy. He had to mark a boy as his equal. He chose Potter and sent Bella, Rabastan, and Rodolphus to kill the Longbottoms. That night was the first time I saw Bella cry. The family was innocently sitting at the dinner table when Bella and the Lestrange's arrived. She scooped up child while her husband and his brother tortured Frank and Alice into submission. She did not protect the adults from their torment. She saw no need. They were the enemy. The child, however, would grow old hearing his parent's screams. She sneered at her companions to leave her to finish off the parents, modified their memory so that Neville was not in the house at the time, and sent them on their way.
Bella did, in fact, finish the job that night. Frank and Alice were little more than living when she was done. But the boy was safely deposited on the front step of Augusta Longbottom's home.
It never occurred to her that the Longbottom parents faced a fate worse than death at her hand - the child was safe.
When she was arrested for her crimes that very same night, she fell completely into her madness at the thought of never seeing Draco again.
Narcissa blinked, pulled from her reverie, and regarded the young, battle torn witch, who sat in her parlour. "I know the woman you were tortured by was cruel. Mad by all accounts. You did not deserve it, Hermione. But do not blame yourself for my losses. I finished the war with my husband and my son alive. I lost my sister long ago."