The story line is kinda but not really but kinda the same but modern k thx (if this makes any sense)

"Sebastian, I've told you this before, I don't need you to protect me. I'm a big girl now." You sighed as you and Sebastian were both getting ready to solve a case, ordered by the Young Lord Phantomhive. You weren't contracted to the Lord in any shape or form, but your brother, Sebastian, was. That meant that you stuck by and did whatever it was that was needed to be done, mainly because Sebastian didn't want you getting hurt and this was the best way to keep an eye on you. He wasn't doing the best of jobs.
Every other night you would sneak out to meet the 'love of your life' as you put it, cheesy as it was but it was true. You had never felt like that about anyone and you have been around for a long time. You're not as old as Sebastian, no. You're his younger sister, which made him more protective. What made things even worse was the fact that we would never approve of your boyfriend so you never told him.
And that all brings you to where you are now. Waiting outside, in the cold, waiting for Jack the Ripper.

"You know I watched a Tv series once, there was a vampire who was referred to as a Ripper. That seems more exciting than this." You let out a long, irritated sigh.

"Please stop talking about that stupid vampire diaries show." Sebastian gave an innocent yet sarcastic smile, one that involved him to tilt his head slightly and close his eyes. You were about to hit him when a scream could be heard, shattering the silence of the cold London night. Sebastian and Ciel were by the door in no time while you stood back, blood not being your most favourite thing in the whole wide world. When Grell walked out you were shocked. Just because you were always going to cases with the two didn't mean they told you anything at all, but you already knew Grell was a Grim Reaper due to the fact that you had bumped into him multiple times, not by choice. You patiently waited for him to get out of the disguise that, honestly, looked terrible on him.

"You look better in red, my love." You winked as you shifted slightly, the wait to do something obviously bored you. Madame Red was also a problem but you didn't think much of her, that was until she pulled a knife out and slashed Ciel's arm. Before he could even say a word you were behind Madam Red, your hand in her chest.

"I will rip your heart out." You spat. Just because you weren't contracted to the Young Lord didn't mean you wouldn't protect him with your life. You could see Ciel was about to say something but you acted first and pulled your arm out of her chest, her heart in your hand. You watched as her body fell to the floor before turning around and throwing the heart at Grell. He was surprised and disgusted at the same time (it wasn't everyday someone threw a fresh heart at him and he didn't like it).

"One down, another to go." Sebastian whispered to himself as he got into a heated fight with the Reaper while you stayed near Ciel and waited for the inevitable. Ciel stared at the lifeless body of his aunt which caused you to shuffle away slightly. He wouldn't hesitate to get you killed and you didn't feel like fighting for your life against your brother.

"Just kill him and let's go brother." You sighed as you looked down at your nails, feeling a wave of boredom hit you. Grell was already on the ground while Sebastian had his death scythe. He pulled his jacket out and it started up again, but before he could end it all you saw that oh so familiar scythe. You looked at Sebastian and William with caution, watching there every move which Ciel noticed because he smirked slightly. He had just watched you kill his aunt when that was not what he wanted, even though his orders were to kill Jack The Ripper so he was going to test something out.

"Sebastian, leave Grell alone and kill him instead." Your heart stopped when you heard that sentence leave his mouth. You thought maybe you heard wrong but when you saw Sebastian bow, you knew you had to think fast because this wasn't going to end will for you. That's when a thought hit you, a stupid one but a thought none the less. As you walked up to Grells body, Ciel was curious. Were you going to help Sebastian kill William? That was an easy answer. No. When you were in front of the almost unconscious Grim Reaper you picked up his death scythe and turned it on, this caused the two males to stop fighting and to look at you.

"[Y/N]... What are you doing?" Sebastian asked. He knew you weren't going to fight William, because he had guessed that you two were a thing when he finally figured out that you had been sneaking out.

"Me? I'm just playing with this, I'm not sure what I'm going to do yet. Might plunge it into Ciel, might plunge it onto myself. Whichever seems more convenient when the time comes." You said as you acted like nothing you had just said was wrong. You looked over at Ciel who had a shocked look on his face. No one has expected things to turn out the way they did so you decided to carry on.

"So here's how this will go. Either you both stop fighting, we let Grell go and go home to pretend like this never happened, or you carry on and start planning a funeral, because once I plunge this into one of us the fighting will sure cease."

"If you try and hurt me Sebastian will kill you." Ciel spat. You nodded in understanding.

"Do you think he would be able to? Kill his little sister? That's like you killing Lady Elizabeth, the one you go to so much trouble in protecting."

"You're bluffing."

"I can assure you she is not." William finally spoke. Sebastian seemed angry at the sound of his voice but controlled himself as everyone's eyes were on you.

"I'll take the chances. Sebastian, you have an order to complete." Ciel almost shouted. Now, you weren't stupid, you knew this wouldn't end will for you but you had gone through too much emotionally to lose another person close to you because of others selfish acts, so you did what you said you would. You turned the scythe around and pushed it into you, causing a scream to leave your cold lips. Everyone stopped what they were doing and looked at you again as you were bleeding out and your cinematic records could be seen, but before anyone could delve into your past Sebastian pulled the scythe out and disappeared, with you in his arms. He had broken a few rules on the contract but none of that mattered while you were dying, but you thought it was worth it if it meant they wouldn't die. If it meant you could keep someone close to you safe.

A/N
So this is the part where I say my excuses. Basically. I had important exams, and then I had prom yesterday and my mum moving out has been happening and I had no motivation oops.

Ciel: Why am I the bad guy here?
Author: Because you can't always be 'good'
Ciel: I disagree.
Author: Course you do, small fry.