Here's a revised version of your excerpt, with improvements in grammar, clarity, and flow:
"See, Void, you know very well that I'm the one who helped you gather those clips you showed to Her Majesty," Rubianna said, her tone dominating, her voice like a gun ready to shoot.
"Yeah, I know that very well. And I can't forget such a big favor. You were the only one handling both cases," Void replied, maintaining a slight smile on his face. In his mind, he thought, "I just have to agree with everything. Yes, I just have to survive and protect everyone!"
"I'm glad you still favor me," Rubianna said, setting her cup down. "Void, there's nothing to be scared of!" She locked her gaze on him, her eyes sending chills down his spine.
"That Shuri! At first, I thought she was just a naive girl trying to befriend everyone. But she's taking my Charles away from me! Who gave her the right to lay hands on my man?" Rubianna slammed her hand on the table.
"Did you talk to her about this? I mean, we should give her a warning, don't you think?" Void asked, thinking, "I don't know if this will work, but negotiation is the first option."
"I did, but that bitch... I can't forget what she said that day," Rubianna recalled Shuri's words.
"Huh! Is it my fault if you guys like to hang out with me more than with you? Don't you think it's better for you to leave him and get some other bastard who can take all your demands and shit on his head!" Rubianna repeated Shuri's words to Void.
"She knows exactly what she's doing! And I... I can't do anything. I tried to make Charles feel cherished by me, but it's no use. I can see him slipping away each second. Every time I close my eyes, I see the distance between us growing," Rubianna said, tears forming in her eyes, her words cracking as her heart broke with each mention of it.
"So what do you want from me, Ruby?" Void asked, giving her clenched hand a warm, reassuring squeeze. His voice was calm, the shaking of his legs faded away. In his mind, he thought, "If I'm correct, Arcane and Alfrin are by her side. I removed them to make her helpless. It's my mistake that I'm making her unable to protect her love. Not that she can save him either; but I can give it a try. Shuri's not just her opponent; she's scripting my death too!"
"Ehehe!" Rubianna let out a slight chuckle, wiping her tears, regaining her composure. She removed the gun she had kept aimed at Void's head all this time.
"I want you to fight Shuri. If the time comes, I'll need you to stand by my side to duel Charles!" Rubianna said, a wicked smile playing on her face, her crimson eyes glowing with a hint of the madness growing inside her.
"Charles! Are you serious? You know well, Ruby, that I fight either to kill or to break the will," Void said, shocked by Rubianna's request.
"Of course! I know your potential. But see, I can't fight Charles, nor is there a strong male magician who can fight him…" Rubianna finished her tea.
"And moreover, I want you to break his will! I'll take all the responsibility if things go wrong. I need you to help me get my man back, even if it means breaking him for that!" Rubianna said, a confident smile on her face, though her eyes showed the pain and suffering she was enduring.
As she finished, she waited for Void's answer, a slight smile more like a grin on her face. "I see. It's not like I have an option here. I'm in!" Void extended his hand, and they shook hands, sealing their agreement.
After some light chats, Void was on his way back when he saw Vivienne, who seemed down and angry, punching the wall.
"Why! Why! WHY…!" Vivienne muttered, her tone filled with anger, tears dropping on the ground. She suddenly noticed Void's presence and wiped her tears, keeping a hand on her reddened cheek.
"Did something happen, Vivi?" Void asked, walking towards her, his hands in his pockets, his face showing a smile with hidden concern.
"Nothing... Absolutely nothing. I just lost one duel, hehe!" Vivienne said, trying to fake a smile, putting up an act.
"You know what! It's okay to lie to others but not in front of me, your big brother!" Void said, giving her a pat on the back, rubbing it to calm her down a little.
"Now, let's have a sibling chat, shall we?" Void said, starting to walk forward, waiting for Vivienne to join him. With a light chuckle, she started walking beside him.
"I sometimes mistake you for a girl with a flat chest! That's how feminine you are!" Vivienne said, her tone still a little dead.
"I'm Middletown's future head. Of course, my behavior and personality must stay strong!" Void said, letting out a haughty chuckle. "Moreover, don't hide it… you didn't just lose a duel, right?"
"I... actually... I saw Leonard kissing Shuri!" Vivienne said, her eyes looking lifeless. "When I talked to Leo about this, he just said I'm annoying him. I'm not up to his expectations, and Shuri... Shuri is the only one who understands him!" Vivienne bit her lip, tears streaming down her face.
Void gave her a strong pat on the back, making her stumble four steps ahead. "Huh! And you call yourself the daughter of Maria Middletown! Whining after getting rejected by that guy?" Void said, summoning his blade, a grin spreading across his face.
"That's not my Vivi! She's my taunting, bratty little sister. Is there only one guy in this world? Has your whole life ended after that brat ditched you?" At first, Vivienne was angry over how Void was acting and what he was saying, but that made her realize their positions and what Void meant.
"That's right! Void knows the feeling of being ditched. He was ditched by me first! After that, even generating feelings, he fell for Aoi, but she too rejected him. But he didn't give up nor did he ever feel sad over it. Even after that, he's nice to me! Nice to Aoi. He moved on..." Vivienne thought to herself.
"And hear me out, Vivi! Leo will surely know your value. Trust the time and keep focusing on your progress. Don't disappoint Mother; you won't be getting into the underworld, you know! See ya!" Void said, laughing haughtily. Vivienne regained her composure and said,
"That's the wrong way, you idiot! You'll again go to the dark side. Your room is on the opposite way!" Vivienne said, opening the door to her room. "The future Middletown's head... blah blah!" She got inside her room, saying that.
"Oh! Thanks!" Void turned around. "Shuri Lux! You've already made three different opponents, and there are more male leads who are not even here. As the game's event will take place, a ballroom where all the students, higher or lower rank, will get together;
That's when Rubianna will find out that Shuri is not just having an affair with Charles but also with Samuel and Leonard. According to the game, Arcane and Alfrin help her in this event! Well, it's not technically even a fair battle, but who gives a shit!
And if we stick with the story of the game, Rubianna will lose and get expelled. She'll be charged heavily, and I don't think she's even mentioned in the game after that…" Void thought, passing his room and entering the ship's deck, where it was already nighttime.
"The hell! How will I get back now…!"