Intro: As an author's note, I'd like to set this up, since the storyline isn't perfectly 'canon', and if you don't understand what's going on, this will mean nothing to you.
In this piece, Bellatrix, Rodolphus, and Amycus would all be about twenty-one, twenty-two perhaps; Rodolphus and Bellatrix (whose arranged marriage became legal immediately after graduation) and several others are all together at Cygnus and Druella Black's home. This certain instance is set very late at night, probably 2 am or so. The main thing to know here is that my Amycus is a monster.
He fell in love with the young and wild Bellatrix Black when he was only a boy, and wanted her desperately. When they were fifteen, an awful game of truth or dare had them breaking into Cygnus Black's liquor cabinet and ended with a wasted Bellatrix leading a not-as-tipsy-as-he'd-have-her-believe Amycus into a greenhouse. Thus, he's won the first Black sister - and her chastity. They were together briefly, but Amycus joined the Death Eaters early into the start of the new school year. Afraid of the power hungry monster he'd become, Bellatrix dumped him and focused all of her attention on winning over her husband-to-be, Rodolphus. Amycus, however, was not completely (or even slightly) over Bella, and decided instead to seek his revenge by targeting her sister, Andromeda. Which brings us (eventually) to Amycus stealing the second Black daughter's purity.
Eventually, Rodolphus gives in to Bellatrix, and by the time of their parental-enforced marriage, they are the epitome of young love. They were so strong, and Rod was incredibly protective of his wife, though she was wild and believed that she was invincible. He knew, of course, of Bella's early fling with Amycus, and never got over the fact that (though he'd had a dozen other girls in his school years) he wasn't her first and only lover, and even more hurt by the way Amycus used this against them at any and every opportunity. He is completely angered by Amycus' very existence.
Years later, the night before Narcissa Black's wedding, Bella and Andromeda are resting slightly easier. He's lost, for surely a wedding band will stop Amycus' wild venture to complete the set; a vendetta that had all but consumed him since that day Bellatrix Black left him, humiliated, in the Great Hall. Amycus seduces and charms her out of her virginity as well.
I think that clears everything up. At least, I sincerely hope that I haven't left anything out, because this piece actually moves me to tears when I reread it because it means so much to me.
"Don't you find it interesting?"
The voice from the darkness here in the kitchen he believed to be empty startled him; he whirled around with his wand already aimed, though his target did not breathe even a sound of fear.
"Easy, killer," she smirked, pushing the twig away with a single finger. "Aren't we quick on the draw tonight."
"What do you think you're doing?"
"It's my house," she scoffed, setting her mug down next to where she sat on the countertop. "I ought to be asking you."
"It's your parents home, Ella. There is a difference, now." The ice on now chilled her, reminded her of a million dark days, of the way his presence never did quite leave her, just as he'd never quite had her. He leaned back against the counter with a resolved sigh. "I can't sleep."
"Like any of us can. What's troubling you?"
"You would but look around to know."
"I stay out of the trivial affairs of others. If you do not so wish to enlighten me, so befit this darkness," Bellatrix smirked, her fingers wrapping gently around the coffee mug.
"I would never trouble your sweet mind—"
"Hah! Surely you're joking. You of all people know just how to keenly navigate those shadows." Her eyes were unforgiving, drilling holes into his skin in the dim candle light.
"Be that as it may, dear Bella, you're much happier now than you were in those dark days."
"You've not answered my question, Amycus," said said airily, deftly diverging the discussion as she slid down from the counter. "Don't you think it's interesting?"
"Think on what, pray tell?"
"That you can break your brother's toys," she hissed, slipping closer now with venom in her words. "Yet none may near your prize."
He swallowed, his eyes not yet giving him away. "I do not understand."
"Do not underplay the fool that you are, Carrow; at least pretend that you have a spine."
He thought a moment before he truly recognized his crime, his sins seeping through his smirk. "So you've spoken to Narcissa, then."
"We all knew of your demented plan, Amycus. But most of us thought you would not be so crazed as to betray a brother in pursuit," she pushed, her voice growing louder to match her anger.
"That's no business of yours," he growled, his eyes narrowing slightly; the monster she remembered being reborn there in a flash of hatred.
"How can you —-" her protest cut off by his hand covering her mouth, the mug shattering on the floor. Her hands, clenched into tight, frail fists, pounded against his chest as he pushed her back against the wall.
"I've completed the set, my dear, just as you knew I would," he hissed into her ear. She dug her nails into his skin, bit down on the skin she could manage; any attempt to coin release. "I will release you, pet — for I'd love to hear your response — but you must promise you will not disturb our housemates." She made no effort to either agree nor object, and slowly he removed his hand, stroking her hair in a demonically possessive way.
"We were children, Amycus. In age you may not have been my senior, but in knowledge you far surpassed both me and my sisters and you abused your power. We were children and you abused us," she said, her tone hurried but lowered as promised. "I will never forgive you for the damage you have done to me."
"Has that seed blossomed so? Is it fear you feel, sweet, sweet Bella?"
"Fear? I would never allow you to feel the honor it would bestow to say that I fear you, Amycus Carrow," she hissed. "Truth brings knowledge. I know plenty of what you are, who you are. You are a monster, a god forsaken demon, and I pity your soul."
"You pity me, darling?" he smirked, twisting a piece of her hair between his fingers. "You are quite the hypocrite, for surely you know that your hell will burn twice as hot as my own."
She took advantage of his distraction, ducking under his arms and darting away from him. But being the quicker of the two, the one trained for accuracy, when he lunged, his hand clasped easily on her ankle.
But the rough hands that lifted her from the floor did not belong to Amycus Carrow, but rather to her keeper, her husband, her Adonis. "Go to bed."
"He —"
"Bella, go to bed."
She obeyed quietly, her anger echoing in each step up the stairs.
"You've disgraced their entire name, and yet you feel you must disgrace yours as well," he said, picking up the larger pieces of glass from the floor. He would not meet Amycus' eyes. "You've destroyed her and that is still not enough."
"She is nothing that people believe. She is everything human of hatred, fire, and insanity."
Rodolphus crossed the room in a sweep, his lip curled in anger. "She is my wife, and if you should ever lay hands on her again, I will kindly escort you to the gates of your fiery eternal home personally."
Amycus did not speak, but merely pushed off of the wall and disappeared down the hallway.
"He's to blame for any fault that Bella might have," the tiny voice in the corner spoke out now. a spark from her wand and the candelabra lit, shining onto the face of the blonde sister. "She was perfect, would have always been perfect, were it not for him."
"Amycus Carrow is many things, Narcissa, but a puppeteer is not one."
"You would be very surprised over the manipulation that man holds, even still, on my sister."
The thoughts he never allowed himself to imagine, the dark days in school before he realized the pricelessness of his gem rushed back.
"She hates herself every day. That she would never admit it to you is appalling, but not irrational. She pretends that those days with him never existed, because she would like to believe that her life has only ever circled you," Narcissa pulled her knees up to her chest, wrapping her arms around them.
"Why are you telling me this?" Rodolphus sighed, rubbing his forehead.
"Because you are far too precious to her to not know the truth."
Just for fun!
My headcanons for this era are SO thought out, haha. I know exactly what they look like!
Bellatrix Black Lestrange - Troian Bellisario
Rodolphus Lestrange - Ian Somerhalder
Narcissa Black Malfoy - Amber Heard
Andromeda Black Tonks - Gemma Arterton
Amycus Carrow - Matt Bomer