A/N: It's finally up! Took me ages, I know, and I'm sorry! But I rather like how it turned out. This is my third and final entry into My Dear Professor McGonagall's Sibling Rivalry contest. I'm kind of excited about this one because I absolutely love writing about Sirius from other people's POV and if I ever find the time and pluck up the nerve to start the Marauders story I've been hinting at for ages now, this is something of a preview in a way. :) So anyway, I hope you like it!

Oh, BTW, I disclaim.

On the topmost landing of Number Twelve Grimauld Place, a door swung open silently. The candles in the chandelier guttered in the draft, but the rest of the house went unaware of the movement. A young man stepped out of a dark bedroom, hesitated for a moment, then quietly closed the door behind him. He turned to face the empty landing.

There was rigidness in the way he stood, a passive mask held firmly in place by an aristocratic aloofness so deeply ingrained, it came without thought. But that night his eyes gave him away, pale and filled with some wild emotion that set his entire image off-kilter. The young man stood quite still, slight frame swathed in a dark traveling cloak, oddly lost and young in the dim picture.

He slipped a hand into his pocket and withdrew something that glinted in the flickering candlelight. A small golden locket lay in his palm. He gazed at it for a moment, following the hypnotic swaying of its delicate chain before closing his fingers around the cold metal in a white-knuckled grip and sucking in a sharp, steeling breath.

That was when his eyes fell on the second door on the landing, one that had virtually faded into the plaster during the last four years. As if drawn by unseen forces, the young man moved towards the door, reached out a hand, pushed on the handle. Locked. Just as Sirius had left it. And no one had bothered to test the room until now.

He could have sprung the lock with a flick of his wand, but instead – maybe to prove something, or to feel again like the snooping younger brother he had not been for so long – he moved sideways, running his fingertips along the peeling edge of the wallpaper until he found the section that gave easily, hidden behind the corner cabinet. Nimbly, he drew out a tiny brass key and slid it into the keyhole.

The second door squealed on its hinges as it swung forward. Fitting. Sirius had always been the louder one, incapable of doing things with stealth or without protest. A rush of stale, dusty air hit him along with the eerie, undisturbed feel of vaults and prisons. That room had been both.

He squinted into the gloom. Cold moonlight forced its way feebly through a gap in the curtains, falling like another layer of dust on the elegant bedframe, the poster-plastered walls. He raised his wand and in one almost imperceptible motion, coaxed the old candles into igniting and illuminating the grandeur that, in four years, had fallen to decay.

It should have been like looking into the past, this time-vault of a room, but he could see only the future. This was how it would all be, if things went to plan, if tonight would ever mean anything. The glory and riches of the others in houses like this would crumble, the families themselves withering away in a sunken shell of former majesty.

Or maybe not. It was a tiny thing he was doing, really, in the grand scheme of things. His role would go unknown for who knew how long. It may not make an ounce of difference in the end. Someone else must find out this secret, and then must find some way – some impossible way – to do something about it. All he was doing was moving one of the pieces around. Was it worth it? Ought he to turn around right now and fling the locket from his bedroom window, not throw everything away on a pointless gamble? And even if he wanted to, could he go through with it?

Those roving, pale eyes settled on the wardrobe door hanging slightly ajar.

Slam!

The wardrobe door hit the frame so hard it bounced back.

"What are you doing?"

"Getting the hell out of this effing place! And if you knew what was good for you, so would you!"

"They won't let you leave."

"Let them try to stop me."

He pulled out his wand then and the fury twisting his features, the intensity radiating off him in waves made him look on the edge of terrifying. For a moment, it seemed that nothing could stand a chance against him. He closed the trunk lid with another slam and shoved his way past, into the corridor.

"And where are you planning to go? No one will take you. Not after this."

"Then I'll live in a fucking box and it'll be a damn sight better than here!"

Bang! Bang! Bang! The trunk crashed into each step, rattling the house as he raced downwards, already running away.

"They won't let you come back!" It was a shout now, as they raced for the ground. "If you leave, it'll be for good! You won't ever be allowed back!"

"Thank Merlin!"

"Sirius!"

They had heard. The screech echoed around the entrance hall as they appeared at the top of the stairs from the kitchen. Mother's face was twisted, Father merely watched.

"What are you doing?"

"Leaving," his answer was short and harsh and he was across the floor in a few swift strides, ignorant of her screeching.

The door swung open and frigid air swung in from the night. He made to slam the door behind him, to be done with them all for good, but half-way through the motion changed his mind.

"You're sick bastards, the whole lot of you, you know that? If there was a shred of humanity left in you, you'd realize what you're condoning – what you're doing – is evil. I'd rather throw myself off the astronomy tower than be anything like you!"

And with another slam, he was gone.

That was when it had started. He had easily slipped behind the cool indifference he had long since been practicing. It was terrifyingly easy to blot his brother out of his life, pretend as if the room opposite his own had never been occupied. But a part of him had been shaken, he could not deny that now, looking back.

For all their arguments and ignorances, for all the distain and disappointment, being left had left a part of him hollow. That solid presence, for all its mutiny and furor, was a fixture he had unwittingly relied upon to balance the world. And with its absence things had tipped out of control.

It was easy to be angry with Sirius, easy to blame him. He had joined them to make up for his brother's failures, to prove beyond a doubt that he was the perfect son, and his parents had been proud. There had been no one here to stop him, no one to tell him he was going too far, no one to tell him what a deplorable person he was becoming. And when his eyes were forced open to it, there had been no one here to pull him back.

Now this was his only way out, his only chance at repentance. Was it even worth taking?

His eyes landed on something else in the room; a photograph fixed to the wall showed four boys. For once Sirius's face was not contorted with anger or disgust or bitterness. He was laughing with the rest, happy and carefree.

And the boy next to him, with the messy black hair, who had accepted Sirius into his house with no questions or conditions four years ago, he had been the brother Regulus had not been.

The Dark Lord was chasing after a baby. A family. That boy's family. Sirius's family.

Regulus let out a slow breath, sliding a hand into his pocket to touch the cold metal again as he stared at the picture. It might not be in time for him, for his son. But then again, it might be.

He stepped forward, tried to take the photo from the wall in case he needed reminding when it came time to let go. But it would not come. He let his hand drop, and turned away, clutching the metal all the more fiercely.

Sirius had been right that night that he'd left. What they were doing was evil; it always had been. He saw it now, and could find no way out. Devoid of the astronomy tower, this would have to do instead. And it was worth it. Sirius would have done it. He would have done it for James.

He did not look back as he left the room, let the door shut and lock behind him and left the candles to burn themselves out. Maybe mother would come up looking for him and see the light under the other door and be reminded, for just a second.

The cool mask had slid easily into its place as he drifted silently down to find Kreature. Sirius had left this house in his fashion: a loud storm of emotion. He would slide away silently, almost unnoticed, as was his fashion. And they would finally both have escaped.

A/N: ? Did you like it? I'd love some feedback! And some votes on my poll, too as it all is going towards that Marauders story. Thanks!