Brother My Sun, Sister My Sea
It is my impression that there is a serious lack of Black Lagoon fanfiction in general, let alone anything about the twins, so I've taken it upon myself to try and remedy this. As with anything involving the twins, there's probably going to be some fairly disturbing content, thus the M rating. Just a warning.
As always, I am not affiliated with the manga-ka, their publisher, the licensor, etc. I am but a humble writer hoping to entertain. Enjoy.
"Let's go for the Ruskie."
The faint glow of a lone candle flickered in the corner of the room. Its fire crackled and sputtered, wax dripping down slowly before hardening again farther away from the flame. Such low-lighting was the breeding ground of shadows; the same kind of shadows they had been used to their whole lives. And they couldn't stand the harsh artificial lighting that seemed to be everywhere. A simple candle would do...
"No, Sister."
She tilted her head. The shadows danced on her skin, the candlelight illuminating her soft features. He wasn't looking at her, though - his gaze was cast downwards at the pool of blood beneath him that had long since stopped growing and now sat stagnant, inanimate but for the way it glistened and turned black. But he could see her in the corner of his vision. And she was beautiful.
"I mean about them."
"Oh!" She let out a small laugh, kneeling down on the other side of Ivan's seated corpse. "Let's just kill them all."
That innocent smile never left her face.
He loved that smile. He loved seeing it on her pretty face. It belonged there, just as much as her petite nose and bright grey eyes did. It was troubling to think that for so many years, that smile had been completely absent...and now it was there naturally, for the same reasons that it hadn't been not all that long ago.
"I hate getting yelled at and spanked. It makes me want to cry."
He didn't like it either. More importantly, he didn't like seeing her cry. He had seen far too much of it already - enough to last the rest of his life. As her happy eyes searched for his, he glanced away, now staring at the door that had yielded such an unwanted intrusion a few moments before. An intrusion that had interrupted her lovely singing voice. That, too, had been all but lost, up until recently.
"Right, Brother?"
He hesitated.
Let's just kill them all.
Rising, she reached across Ivan's lap and placed her hand on her brother's, beckoning for him to follow. The act made his eyes rise to meet hers, and in them he could see a hint of mixed worry and confusion. He smiled softly, though it didn't seem to come as naturally to him as it did her; it was more a smile of reassurance than of actual happiness. It was saturated with uncertainty. Her own smile faded a bit upon finally realizing his hesitation.
"...It smells so strongly of blood, Brother. Let's go take a bath."
"But it smells so good." Her hand tugged impatiently at his, and he relented, shaking his arm lightly to separate the blood-soaked sleeve from his skin. He breathed deeply, closing his eyes as the coppery scent of the cooling blood filled him. By the time their bath would be done, the smell would probably be faint, or gone completely.
"It's such a shame, Sister..."
She locked the door as she passed it, making sure no one would come in to interrupt them again. The curtains were drawn closed, perhaps for no other reason but to erase the annoying glare of the street lamps outside, but it gave them peace of mind for their privacy. The candle was carried with them into the bathroom, placed by the sink, where its flame could be reflected by the mirror, giving more light than just the flame by itself. The bathroom wasn't at all spacious, but then again, it didn't need to be; the company of each other was valued so much more than being alone.
Placing it gently next to the sink, she reached down and grasped the hem of her little white babydoll and lifted it over her head, gently folding it and placing it just outside the door. His socks and shirt joined it as the water began to run, drowning out the noises coming from the outside world. He shut the door.
"Don't forget to wash your hands, Brother."
Turning, he blinked a few times as his eyes adjusted to the light. Her hands were beneath the faucet, the running water turning dark as it rinsed the blood from her skin. So much of it still stained her beautiful platinum hair, the dried blood acting like wax, making her locks stick together. And the scent of death still clung to her body...
"Sorello..."
"Da, Fratello?"
His arms had looped loosely around her neck, pulling her close to him. Kneeling behind her, he rested his chin on her shoulder, loving the feel of her soft skin against his. Her scent flooded him; he shivered as he took a deep breath, exhaling softly against her ear. For a few moments, he simply indulged in that pleasure, allowing his hands to explore her chest as he gathered his thoughts.
"Sorello," he repeated, "do you really want to do it?"
She turned to look at him, an expression of confusion on her face.
"Kill the Ruskie, Brother? Why not? It would certainly be fun." The smile was starting to come back, but her brother said nothing in response. Now she was the one affected by hesitation. Her lips worked as if to continue convincing him, but no words actually came out. There was something in his eyes she wasn't sure she liked. And then in an instant, his mouth was on her neck, nibbling gently at her porcelain skin. Her lips parted in a soft gasp, warmth rising throughout her body and collecting between her thighs. Her breaths quickened as he teased.
"Brother..."
"It's not worth it." His hand was quickly finding its way downwards, lightly pressing his fingertips into the notches of her hips; his reward was a soft moan that was barely audible over the sound of the rushing water. It was overflowing; the sting of its heat brought Gretel back to her senses. Her hand darted to turn off the faucet, too late to prevent a mess. She frowned at the too-full tub; water was all over the floor now, and more would overflow once they got in. The Italians were already so angry with the mess they had made in the bedroom...
"Let's just have our macaroni and leave."
"...Macaroni sounds delicious, Brother." She stood, cautiously stepping into the tub. "But leave to where?"
He smiled.
"Wherever we want, Sister."