Sirius helps him pack the night before his first day at Hogwarts. All of Regulus' books, his new wand, robes, parchment, quills, ink... Sirius has done this for two years now, going into his third, so he knows the tricks to making certain nothing gets lost, how to wrap his quills so the nubs don't snap in transit, and how to ensure the ink bottle doesn't open or break to make a mess of his luggage. Mum has laid out green and silver attire for his first day, and Regulus catches Sirius glancing at it now and again.
When they're dropped off at the station the next morning, Mum kisses his forehead, smoothes his hair—which is far neater, and shorter, than his brother's—and says, "You'll make your family proud."
Regulus wants to. Desperately.
But there's an edge to her tone that makes her assurance sound more like a threat.
Don't let us down, Regulus. Not like your brother did.
He has the strongest urge to take hold of Sirius' hand as they board. He doesn't because he refuses to be seen as some sort of child. But also because Sirius says, "See you at school," ruffles his hair, and leaves him to find his friends. Friends Regulus has heard about but has not met, because one of them is some mudblood boy his parents would never permit into the house, so Sirius never brings any of his friends by. In fact, he was hardly home all summer, in favor of visiting his Gryffindor companions.
(At first, he wrote Regulus every day. Eventually, the owls got fewer and further between, then practically ceased all together.)
He's alone on the train and most of the compartments are already full. The train leaves the station before Regulus finds a compartment near the end with only one occupant—a boy whose robes look a touch too shabby, whose dark hair is in need of a proper cut and tending to, and who doesn't even look up when Regulus slides open the door. He's older than Regulus. His brother's age, perhaps. An upperclassman, someone to be spoken to as a superior rather than an equal. So Regulus lingers in the entryway, uncertain, before inclining his chin and willing his voice steady.
"May I sit here?"
The boy looks up, at first uninterested, then his dark eyes linger on Regulus' green and silver tie. He had honestly thought to wear something different, something neutral, but his mother had conveniently made sure nothing else was available. Eventually he mumbles, "Do what you want," and shoves his nose back into his book.
Regulus relaxes. He slides into the compartment, having to stretch to place his baggage into the rack over his head. The steady sway of the train makes it difficult not to topple right over, but he manages it and sinks into his seat. His companion is reading a Potions book that looks a little worse for wear. Second-hand, like. It makes Regulus a little self-conscious; all of his things are brand new and of the highest quality. Nothing less for a son of the Noble House of Black.
The silence pulls and prods at him as the scenery drags by out the window in blurred greys and browns and greens. He's too used to being around Sirius, who can talk for hours. Or even Kreacher, who knows Regulus gets lonely and will talk just to give him something to listen to.
"Are you a third year?" he finally works up the nerve to ask.
The boy glances up again, looking somewhere between perplexed and perturbed at being bothered again. "Pardon?"
Regulus points to the book in his hands. "Third year Potions. And Slytherin?" Because he's wearing the same colors as Regulus. Really, it's the only splash of colour on him. Everything else is black and white, black and white. His eyes included.
"And you're a first year," he responds coolly. "You're wearing house colours. Confident of where you'll be sorted, then?"
No, Regulus thinks. He isn't sure of anything. Because his family was positive Sirius would end up in Slytherin, like every other Black before him, and now that Sirius has failed the task it's up to Regulus and he doesn't know where he wants to be, what he wants to do. He wants to be with his brother, wants to make his parents proud. But what pleases one always displeases the other.
But his mother wouldn't like such a response, and Regulus is desperate to go into school with at least one person aside from Sirius who might be his friend. So he says with feigned confidence and casualty, "Of course." And he offers out his hand without reservation. "What's your name?"
A faint, thoughtful frown has creased the other boy's brow; he eyes Regulus' hand like he's expecting it to bite, but eventually, slowly, takes it. "Snape. Severus Snape."
"Snape," he repeats, a slim smile pulling at his mouth. "Regulus Black. A pleasure."
Just like that, Snape jerks his hand away as though burned. His eyes narrow. "Black, you said."
"That's right."
"You've an older sibling."
"I do." This, Regulus says with pride, because Sirius is someone he admires—Gryffindor or not. "He's a third year, like you. Do you know him?"
"Yes." Everything about Snape's demeanor has gone frigid and for the first time, Regulus notices how sharp his features are, how piercing his eyes, and it makes him uncomfortable, leaves him wishing he'd not been so foolish as to open his mouth about his brother. Snape says nothing further. He buries his face in his book and for the remainder of the trip they ride in uncomfortable, icy silence.
Regulus is never so happy as when the train rolls into the station. Snape rises, smooth and silent, snatches his things and is out the door before Regulus knows what's happened. He's slower about fetching his own belongings, making mental note to ask Sirius about it later. It wouldn't surprise him that his brother has enemies at school. But he curses his luck that it would be the one person he happened to sit with on the train.
Outside, the night air is biting and thick and cloudy. Prefects shout and gesture, herding students about in the fog. In the chaos Regulus only briefly catches sight of his brother parading along and laughing with three boys Regulus assumes to be his infamous friends. He tries to catch Sirius' eye, hoping for a smile, a wave, some sort of acknowledgment.
Then they're gone in the crowd, and Regulus is ushered off with the other skittish, anxious first-years. But he tries to reassure himself Sirius was looking for him, too.