For the big sis/lil sis comp – character: Regulus, word: soul, phrase: piano keys, emotion: abandoned, item: sheet music.

Companion of sort to Laura's the pattern of his skin.

i

You make your way through life playing people like the piano that you learned to play as a child. You know what keys to press and in what order to change their rhythms to Regulus Regulus Regulus. It's the only way to achieve the power that your parents have kept from you.

But just like all things, the sheet music of your life comes with an unexpected change.

ii

His name's Gideon Prewett and he doesn't know when to leave things alone. He's infuriating, annoying and oh, so Gryffindor. He follows you around because he thinks you need a friend, and no matter what insult you throw at him, he never gets the hint.

You can't seem to rewrite his rhythm to your liking. He's a challenge that you've never encountered before. And for some reason, it intoxicates you.

iii

By the time that you manage to press all the right keys, it's already too late. You're in too far. While you managed to make his heart steadily beat Regulus Regulus Regulus, he got yours to tap out the rhythm of Gideon Gideon Gideon.

It scares you how easily it was changed. But then again, you've never let anyone as close to you as he has gotten. He's tapped his way to the very center of your soul and you're not sure if you can shake him.

iv

Sirius stops you in the middle of the hallway and all you hear is hatred hatred hatred. "Are you going to tell him about Mummy and Daddy's plans for you?" he asks, his tone mocking. When you don't answer, he continues on, "Or are you too afraid that he'll leave you?"

Before he can stop you, you're down the hallway and around the corner. You don't tell Gideon of your parents' plans to have you join the Dark Lord because you know that he will leave when he learns of it. Because Gideon's heart beats good good good.

But you can't bring yourself to let go of him just yet.

v

There's a brand new Dark Mark on your wrist, and pity in Gideon's eyes. You expected some other emotion out of him – hurt maybe or even anger, but not pity. He gives you a sad smile. "I wanted to believe that you wouldn't do this, but deep down, I knew that you would."

You have nothing to say to that because while you never told him of your plans, you didn't keep it completely hidden either. Instead, you whisper, "My apologies," even though you both know that you don't really mean it.

However, he says, "I know."

He crosses the room and presses his lips to yours. All you feel drumming through your veins is abandonment abandonment abandonment even though you knew that it was coming.

It's the price you pay for holding on to him for so long.

vi

There's a boy and he follows you around. It reminds you of Gideon and you find it annoying. But unlike Gideon, this boy is malleable, and his rhythm rewrites easily to Regulus Regulus Regulus.

You've got him wrapped around your finger while your heart – that still beats Gideon Gideon Gideon – is protected by a stone wall. You're not going to make the same mistake twice; you're not going to allow yourself to be vulnerable to this boy.

vii

You hold him close and play his rib bones like piano keys. You tap out a rhythm for him to live by. "The Dark Lord can make you powerful. He can give you a purpose in life, Barty," you hum to him.

He looks at you sleepily. "I already have a purpose, Regulus."

You don't have to ask to know what he means. His heart beats Regulus Regulus Regulus so furiously in those moments that you know that he loves you and you don't love him.

For once, you don't feel any power in that knowledge.

viii

"Take the mark, Barty," you whisper against his lips. "Take it for me. We'll be on top of this world. We'll be powerful."

You see reluctance in his brown eyes, and you hear his heart beating your name. But he nods and says, "Anything for you."

ix

He holds out his newly tattooed wrist for you to see, and you take it in your hands. You press your lips against it, feeling him flinch at the contact.

"Beautiful," you murmur.

When you look up, you see that he can't keep the grin off his face.

x

You're not sure when it happened, when he managed to worm his way pass the barriers that you built so carefully around your heart. But as you listen to the steady beat of Regulus Regulus Regulus, you hear your own heart tapping out Gideon Barty Gideon Barty.

You never knew that two people could live in harmony in your heart, but now you know that there is no changing that fact.

xi

His heart beat has changed – kill kill kill – and you know you're the reason behind it.

The longer you look at him, the more you see the damage that you have done to him. You've lead him down the wrong path because you wanted to feel powerful again after Gideon. You feel guilt clawing at your soul, knowing that you created the bloodthirsty monster standing in front of you.

All because he loved you and you used that.

The only thing that you can do is attempt to strip the Dark Lord of his power to show Barty the truth behind the man he didn't want to join in the first place. You want to show him how to be innocent again. You want to take away his sins.

And you will gladly die to do that, with your heart beating a steady rhythm of Barty Gideon Barty Barty Gideon Barty.

A/n – so many thanks to Kelly for beta-ing this for me.