I don't really have an explanation for this. The timeline's a bit skew whiff but eh.
There's a couple of 'Amane lives, Ryou dies' fics out there, I figured I could try my own. And this really WILL be a oneshot. No ifs or buts, me.
Amane's big brother dies and she knows it should've been her. She's the one who let go of his hand and ran into the road without looking, chasing a cat. She's the one who ignored him shouting. He's the one who pushes her out of the way of the car.
She's not good at any of his games. She doesn't have the patience to paint the delicate figurines or the creativity to bring them to life. She tries to write him a letter one day, but the words just never come and she throws the paper away. She wonders about Duel Monsters but there's nobody around to play with.
Mother dies of sickness the year after. Father might as well be a walking corpse for all she knows. He disappears off to study the world's dead leaving his last living family member behind. For a long time, she feels like a corpse too, or maybe a ghost following just over a corpse's shoulder.
The ring arrives in the post on her ninth birthday, just after dark. She wouldn't have remembered if not for her caretaker's distress that she'd missed it. It's not the woman's fault at all, Amane just doesn't care.
It's not quite pure gold, not like her mother's earrings that she now wears, and it smells of rust and it's nothing like what she pictured when Father said he was sending her a special ring. She can't find a cord for it that night so she leaves it on her desk for the next day. That night she has a dream where countless young men and women are forced to place the ring around their neck. Without fail they all burn to ash and a boy who looks just like Ryou in red watches and scowls. She throws it in a back drawer and forgets about it.
When she turns eleven, she moves to Domino City to go to Domino Elementary - it's the only school that accepts her despite the phrase 'delinquent' surely written in bold red letters in her report. The ring comes with her, almost by accident since she dumped all the clothes that covered it into a box and it just happened to fall in with them. It's forgotten again.
There's a boy in her class named Mokuba, who's hair is as black as hers is white. They're sat together and she thinks she could be friends with him until one day school breaks and he says he can't hang around with her on the roof because his awesome big brother is picking him up from school in person. The adoration in his face pisses her off and she punches him in the face and runs away.
She's called to the principal's office the next day, who suspends her and says she's lucky Mr. Kaiba decided not to press assault charges. When she comes back to school Mokuba sits next to her. She doodles 'sorry' on his sleeve and he gives her a piece of his fried chicken at lunch, but they don't sit on the roof together anymore. The next year Mokuba is moved to a different class because of his spectacular grades and she sits alone. It's the first time she's cried since she watched Ryou's ashes blow away with the wind.
Amane is in junior high when she meets Hirutani. He's a high school boy from a different school but he says her hair is pretty and he's especially impressed with the way she picked his pockets. In exchange for not marching her down to the police station he asks her to go pick up a pack of smokes. She takes three, unsure of which brand he'd like best and he lets her try them. He laughs as she coughs then teaches her how to take control of the burning in her lungs and make smoke rings. The ash at the end reminds her of Ryou's hair.
One day, he wants her to steal something from a boy named Katsuya Jounouchi, who goes to Domino High. Jounouchi is blond and brash and loud and it's so incredibly easy to sneak his phone from his pockets when she spots him on the train. Hirutani ruffles her hair and calls her a good girl when she returns to his hideout. It's the first time she's been praised by someone who wasn't Ryou in a long, long time. He tells her to stay away from the hideout that night, but of course she doesn't listen.
Jounouchi and not-Yugi look at her the same way her caretaker did the time she got suspended on purpose so she could take the train alone back to where she'd scattered Ryou's ashes, or maybe the way Mokuba did when he said they wouldn't be in the same class next year. Hirutani is unconscious in a puddle, blood pooling beneath his head from where he fell. Ryou didn't bleed like that when he died. There was a sharp crunch and his arm was bent where it shouldn't be, but only a few scrapes soiled his face.
He may have tried to kill Yugi and Jounouchi, but she still hates them more. She didn't know why Jounouchi couldn't have just agreed to be in his gang again. The ambulance takes Hirutani away and she never sees him again.
He was nothing like Ryou but she won't let the world get away with killing her big brother a second time.
She digs around in the drawers until she finds the ring, tangled up in Ryou's old sweater. Her skin tingles ever so slightly as she touches the eye in the center. She's seen what the puzzle around Yugi's neck does to him and surely this ring can do the same to her.
She could burn to a crisp doing this, but she wouldn't be able to live with herself if she didn't at least try. Amane ties one of her long abandoned ribbons around the ring and carefully slides the ribbon around her neck.
I will grant you one wish.
A voice echoes in her mind. The shadows in the room grow longer, reaching for her. The ring glows, near blisteringly warm in her hands.
Are there any limits?
I cannot bring back the dead.
Then it cannot grant her dearest wish. She almost drops the ring then and there, but then she sees a shadow that almost looks like it has teeth and she has an idea.
I need you to kill some people for me.
The ring falls quiet for a moment. Then she can hear a low, dark chuckle. It almost sounds like Ryou, playing the part of his most diabolical villain yet.
Is that really it? You stand before ancient magic beyond your comprehension, and you want it to perform something as mundane as murder? Something you could easily do with your own two hands? Modern day children are so lazy.
She hasn't thought of it that way. It seems to sense her indecision.
Why don't you let me take my end of the bargain early? That way, when you finally come up with a wish worth having, I haven't been kept waiting.
Okay.
Amane sometimes wonders if she'd deliberately denying herself a wish. There's an odd thrill watching not-Amane run around. Nobody notices the difference, not one bit. She can't remember the last time she was in control of her body but she doesn't find it any different to how she was after Ryou died. It's nostalgic, like dreadful shapeless sweaters and the smell of paint.
Not-Amane is after Yugi too. He wants the puzzle, but the ancient magic beyond her comprehension apparently has rules and he cannot just steal it from him. Duel monsters makes an aggressive return to her life and together they manage to cobble up a half-decent strategy. It's no show-stopper but the mill deck is wonderfully annoying for everyone they duel, even when they lose.
Eventually not-Amane does win. It never mattered how many times he lost because he only needed to win once to render Yugi and not-Yugi's victories completely useless. He's almost as surprised as she is, then he laughs and laughs and doesn't stop.
Zorc eats Yugi and not-Yugi, then Jounouchi and the others. He eats Mokuba and Mr. Kaiba and the rest of the world, until there's only not-Amane and Amane alone in the darkness before Zorc.
Tell me, surely you've got some idea of your wish now. Third time's the charm?
Does that apply to big brothers?
Then they both laugh. Zorc eats them too and the world ends and Amane's wish is granted.