The sky was dark but for the glistening light of the Black family's namesakes when Regulus finally heard the footsteps and the soft, creaking sound of the door next to his. He knew it would happen tonight, knew it in the way Sirius had remained near-silent throughout dinner, knew it in the way Sirius had smiled when Walburga had pointed it out, suspicious, but proud all the same.
But Walburga had never known Sirius the way that Regulus did, and so she wasn't the one waiting.
Regulus waited, a minute, then another, for the footsteps to reach the stairs. He had always been patient, had always been the one willing to play the long game, and in this one, everything had to be perfect, down to the very timing of the moment Regulus opened the door.
Finally, when Regulus was certain Sirius had reached the stairs, when he had counted to twelve and a half, he opened his door, stepped out, and called for his brother, one last time.
"Sirius?"
The name echoed through the near empty hallway, flung towards the only other living person standing there. The name broke through the silence, shattering the precarious balance that held what seemed to be everything, yet nothing at all, between them. Sirius turned around, wand in one hand, bag in the other one. Regulus could see him tense up, then relax again when he realized just who it was that called him.
That was Sirius' first mistake.
Sirius looked conflicted, eyes slightly wide and lips twitching as if they didn't know what direction to be in. Regulus looked from him to his bag, making sure Sirius could see his eyes widen in realization.
"Reg, I," Sirius started, only to be stopped by Regulus' hand, held out between them to stop him. Regulus plastered a small smile on his face, knowing Sirius could see right through it.
Regulus shook his head, slowly, then quicker-- a habit he picked up from his older brother, from Sirius, when he still looked up to him. "Leave. Go quickly." He let his smile fade slightly, let his eyes grow dim, let Sirius know he was genuine with his words, and let him think Regulus was unhappy with them.
Sirius' second mistake was believing him.
Regulus was an actor. Manipulating his face, his voice and his body meant being able to manipulate others. It was a skill Sirius had never been taught, and one that he would never be able to learn. Sirius wore his heart on his sleeve, while Regulus kept his sewn up and protected.
"Regulus, look. If you want to come, I'll take you. You can't stay here."
There was silence between them while Regulus looked down, then up again, eyes shining with tears. "I have to." He said, and he felt his voice tremble as he spoke. "We can't both leave. They won't let us."
He didn't mention that he was part of them.
"We'll make them. We'll leave, together, Reggie." Regulus knew Sirius had seen the tears, had read his face and believed its lies. It was almost too easy. "They can't control us. I have friends, people who will protect us and fight for us, fight for you just as much as me."
Regulus shook his head. "No, you don't understand." He let his voice crack, let himself sound desperate. "They will hunt us to the ends of Earth. If it's just you-- they'll still have me. Sirius, please, just go."
Sirius reached towards Regulus.
"Please, Sirius. I know how to deal with them. I'll be fine. But you- you have to go. Now, Siri." He knew the nickname would catch on to Sirius' heart, would tear it up, leaving scars that wouldn't heal. "Go!"
Sirius finally nodded, "Okay. Okay, Reg. Be careful, okay? When I can, I'll come back for you, I promise. When Mother and Father are gone, I'll come back for you. I won't let you be trapped by that monster."
Regulus didn't tell him that 'that monster' was the one that Regulus was doing this for.
Sirius' third mistake was not realizing that.
He didn't blame Sirius, who had always been too arrogant for his own good, too proud and cocky to realize he was wrong, to realize that someone he thought was weak-- No, not weak, but soft, was actually stronger than he ever could be. After all, it was Sirius who had bent so easily to the mind of the blood traitors and mudbloods.
So no matter what the others said, Regulus knew he was anything but soft. He stuck to his ideals, and anybody who tried to change them would regret that decision, whether it be sooner or later.
Regulus smiled again as Sirius turned away, a little crooked and more than a little satisfied. Good.
"Goodbye, Sirius." Goodbye, brother. He murmured, watching with sparkling eyes as Sirius left. Left, and didn't look back. He didn't expect him to. He was glad Sirius hadn't, or he might've seen past Regulus' façade.
He supposed his brother deserved a final goodbye, even though he hadn't earned it. Sirius had helped Regulus, albeit unknowingly. With Sirius gone, Regulus was the heir now. Heir to The Most Noble and Ancient House of Black and all the power and wealth within it. He was needed, he was useful, he was no longer the spare, could no longer be thrown away as if he didn't matter.
He almost had everything he wanted.
And yet, if he asked, Regulus knew Sirius would come back to him, come back and save him. After all, Sirius still thought he was good, still thought Regulus was the little brother who cried to him and went to him and asked for him, still thought Regulus loved him more than he hated him.
Regulus knew it, and he relished in it, knowing he had options. He was a Black, after all, and he never did anything he didn't want to, not if he could help it.