My lovely brother
Well this is a small story in middle of chapter 13, when Shinjiro Nagita cheat ryuko to make her wear senketsu, however in this fanfic Shinjiro Nagita and Nui Harime, are two different persons, Shinjiro is her brother and was a creation of Ragyo Kiryuin.
Ryuko: so you cheated me only for make me wear senketsu?
Shinjiro: oh you are really smart Matoi kun, aww but don't be so angry that does not make you look cute, don't you think the same sister?
Nui: yup, yup, ryuko chan don't be so rude with us, we only tried to help you, and now we can play together.
Ryuko: HarimeNui! What the fuck? Are you brothers?
Shinjiro: oh yes matoi kun, and my sister were right you look really cute with that kamui, so cute that I could kiss you. (Giggling)
Ryuko: shut you fucking mouth (attacking him)
One day earlier
Ragyo: Nui, Shinjiro don't interrupt in satsuki's plans she can be really dangerous when she is angry
Shinjiro: well, satsuki-sama said that Nui couldn't enter in the academy, but she didn't say anything about me. (playing with his big knife)
Nui: oh, brother looks like you are not so stupid like I though. (giggling)
Shinjiro: (grabbing nui by her neck ) oh my lovely sister, please don't piss me off, I don't want to hurt you (gently kissing her mouth)
Nui: (coughing) oh… my little brother is upset?
Ragyo: let her go Shinjiro, act like adults and not like children's.
Shinjiro: (releasing nui's neck) oh I'm sorry, Ragyo sama I was only playing.
Nui: oh are you afraid of Ragyo sama? Buuu that's not cool I though you were more brave bro. (sitting on shinjiro's legs)
Shinjiro: sometimes you got to obey Ragyo sama, if she gets angry we can never play together again (touching nui's legs)
Nui: oh, I think that you are right (careless touching his mouth)
Present day
Shinjiro: (blocking her attack with his big knife) oh, look like you are upset matoi kun, but it was the only way to play with you, satsuki sama denied the entrance to honnouji academy to my sister so both ones decided to play here with you. (giggling)
Ryuko: I swear by God that I'm going to kill both of you!
Nui: ok, so try to kill us (showing her the scissor blade) here is your father's sword; come and get it! (smiling)
Shinjiro: oh no sister, I am the brother so I will play with her first.
Nui: aahh, that's not fair, you always do the same. (sad face)
Ryuko: what? I am not a toy, die now you mother fucker (attacking him)
Shinjiro: (blocking, blocking, booking, blocking) I though that you were more stronger matoi kun, please don't disappoint me (giggling)
Ryuko: fuck you! Let's go now senketsu.
Senketsu: right!
Ryuko: senketsu shippu! (transformation)
Nui: be careful brother! Looks like ryuko chan wanna play hard.
Shinjiro: shit, she transformed in flying model.
Ryuko: final technique, LOST FIBER! (cutting Shinjiro's chest)
Shinjiro: agggghhh (falling to the ground)
Nui: BROTHER!
Ryuko: well, I just killed that bastard, it's your turn now Harime Nui. (attacking her)
Nui: I'm sick of this, come on, attack me with all your strength, why are you holding it? (blocking the attack)
Ryuko: I'm not holding my strength!
Nui: (blocking) well I'm gonna end this! (striking, striking, striking) now say goodbye to your kamui.
Senketsu: (screaming and then breaking in pieces)
Ryuko: NO! SENKETSU!
Ryuko fell on the ground and senketsu just broke out in small pieces, then nui ran back were Shinjiro body was.
Nui: brother, are you fine? (holding his head)
Shinjiro: (coughing and blood coming out of his mouth) my little sister… I think that here is were we say goodbye (coughing)
Nui: don't worry I'm going to sew your body and you are going to be ok.
Shinjiro: there… is nothing… that you can do… my little sister (groaning) just kiss me one more time… please.
Nui: (burst on tears) y-yes my brother… I will do anything for you. (giving him a cute and slow kiss on his mouth)
Shinjiro: (coughing and giggling) s-sis you have some blood… on your mouth.
Nui: (crying) I don't care bro, your blood just taste so sweet.
Shinjiro: p-please don't cry (cleaning her tears) I don't wanna see you crying… this is gonna be the last time that I'm gonna see you… so give me a cute smile s-sis.
Nui: ok, ok I'm smiling (cleaning her tears) see, I'm smiling.
Shinjiro: m-much better, agh… (last whisper)
Nui: NO! (crying again) I promise you, that bitch will pay for what se have done. (running back to ryuko's position)
Nui: (about to pierce ryuko body) you are not worthy of dress that kamui, now go and join with your father.
Suddenly satsuki appeared in the last moment
Nui: ops, you got me!
Satsuki: what are you doing here?
Nui: are you angry with me? (slowly about to pierce ryuko)
Satsuki: there is only one fate for those ones who don't obey my orders (cold voice)
Nui: geez, this girl is talking seriously
Satsuki: (smashing bakuzan case against the ground) you want to purge it with blood?
Nui: ok, ok I'm leaving. I just got sick of this girl.
Nui just returned were her brother body position, she grabbed it and leaved the place.
Satsuki: (putting away bakuzan) Pathetic!
Nui just returned to REVOCS and entered in ragyo's office, carrying with the body of her brother.
Ragyo: jum, Shinjiro? What happened to him?
Nui: (sewing his body) that bitch just killed him, but I'm gonna fix him and he will be okay.
Ragyo: (hugging nui) oh my little girl, stop now, that won't bring him back again. Don't worry I'm gonna make a new one for you.
Nui: (crying) I don't want a new one, I want vengeance and I'm going to kill her.
Ragyo: (putting her hands on nui's face) you will get your vengeance I can promise you that (kissing nui's mouth)
Nui: (blushed) thank you ragyo-sama, you are the best.
Ragyo: (smiling) I already know that (spanking nui's ass) now clean all this mess please (leaving the office)
Nui: I promise that I'm gonna make that bitch pay for what she did to you (kissing his dead bother moth) goodbye my lovely brother.
PS: none of these characters belong to me the all are propperty of trigger and kill la kill