Chapter Text
Regulus Black was mad.
Madder than any 9 year old could ever be.
There he was training to be Robin until his father, Orion Black and the one and only Batman, came in with a boy who he claimed was Regulus’ brother. It was so cliché that Regulus refused to believe that this boy who looked exactly like him, only taller, was his brother.
No way.
The same dark curls? Same pale skin? Same piercing grey eyes? Absolutely not, it wasn’t possible that it was his older brother. The only difference between the two boys was their height and the fact that Regulus’ supposed brother had a mischievous glint in his eyes, like he had set up a prank and was waiting for you to walk right into it.
Regulus was an only child… Well, he considered Lily Evans to be his sister, but Regulus Arcturus Black was an only child.
No siblings at all and certainly not this boy who is Regulus’ spitting image that came out of nowhere. No thank you.
“Regulus, this is your broth-,” his father started before Regulus interrupted him.
“No,” Regulus said quickly, crossing his skinny arms while a slight pout started forming on his face. “I don’t have a brother. You’re lying to me, father.”
“I’m serious,” his father frowned at the small boy.
“Actually, I’m Sirius,” the other boy grinned. Regulus gave him a dirty look.
“Well, yes, this is Sirius, he’s two years older than you,” Orion clapped the taller boy’s shoulder, making him stumble forward slightly. “He’s your half-brother. Sirius, this is Regulus.”
Sirius was skinny, like Regulus, but it seemed to be from a lack of nourishment, rather than genetics. Regulus narrowed his eyes at the older boy, like he was assessing every inch of him. Which he was, of course.
“I’ll leave you boys to get to know one another,” Orion said, looking between the two boys. “Regulus, please take Sirius on a tour, Kreacher is making dinner, so I’m counting on you to catch him up on everything, okay?”
“Yes, Father,” Regulus grumbled but nodded as Orion made his way to leave the room.
Regulus stepped forward, eyeing Sirius up and down, sizing him up. In his mind Regulus was contemplating how he could take this boy down in a fight.
“Why are you so skinny?” Regulus snaps at him, the pout growing bigger on his lips.
“I could ask you the same thing, Reggie,” Sirius stepped closer. He seemed to loom over Regulus. 11 was a lot older than 9 in Regulus’ mind. So much more mature, much taller. But not smarter, Regulus was certain he was smarter than this boy.
“Don’t call me Reggie,” Regulus barked at him. “My name is Regulus and you will address me as Regulus, got it?”
Sirius raised an eyebrow at the small boy berating him. He was tiny, like a runt, but the glare he was shooting Sirius made him sure that this tiny boy could easily take him down. He reminded Sirius of a Chihuahua; small and angry.
“Got it?” Regulus’ high pitched voice cut off Sirius’ thoughts.
“Got it,” Sirius nodded. He strutted over to one of the plush chairs that sat against the walls of the training room before draping himself across it. Regulus scowled at that; who did he think he was? Sitting his probably dirty body onto Regulus’ furniture as if he lived here for years.
“So we’re brothers then?” Sirius asked in a rather bored tone, staring at the high ceiling. He pulled a ball out from his pocket and started throwing it in the air.
“Half,” Regulus said quickly, as if defending himself in an argument. “We only share a father.”
Sirius snorted and dropped the ball, it rolling to Regulus’ feet. “Who we both look exactly like and yet you denied me being your brother.”
“ Half brother ,” Regulus insisted, sounding quite whiny by this point.”You’re not my real brother.”
“Whatever you say, Reggie,” Sirius grinned. Which was then quickly wiped off as Regulus threw the ball at Sirius head, making him yelp in surprise.
“You’re annoying,” Regulus huffed, pouting again.
“So are you,” Sirius rolled his eyes. Typical 11-year old. “Y’know, you’re 9 years old, aren’t you a bit too old to be pouting all the time?”
That only made Regulus pout even more. “Where did you even come from?” Regulus questioned with a frown.
“My mum’s womb,” Sirius snorted.
“No! Where did Father bring you from?” Regulus stomped his foot, making Sirius raise an eyebrow. “Did he find you on the streets? You look like it.”
Sirius’ face darkened. “Father brought me back from his last mission.”
“Don’t lie,” Regulus rolled his eyes. “Father was at Tom Riddle’s place... to retrieve something.”
“Why do you think I look like I came off the streets?!” Sirius snapped at him.
Regulus froze. “How… Why did he have you?”
“None of your business.”
A frustrated huff escaped Regulus as his face contorted into a small scowl. “What do you even do?”
Sirius shrugged.
“Can you fight? Or shoot? Do you have any powers?” Regulus continued interrogating him.
“No! Just leave it alone,” Sirius mumbled.
“Well… Well at least I’m training to be Father’s sidekick! I’m bringing something to the team,” he shot back, trying to be intimidating as he puffed out his chest.
It didn’t have much effect.
“Oh, yeah? Not much you can do with those noodle arms, buddy,” Sirius smirked. Regulus felt his face heat up. He knew he was smaller than other boys, even some girls, his age, but at least he was smart. He could make up for the lack of brawn in brains. Plus because he was small that made him agile and hard to spot.
The perfect sidekick, Father had said.
“You don’t need to be strong to be Robin, Sirius. You need to be smart and quick, light on your feet. You must be flexible and be able to go unnoticed,” Regulus explained. “Which is why Father will not be letting yo-“
The door swinging open interrupted Regulus’ speech, their father strode in with a grin.
“Sirius, I have news,” Orion smiled. “You will be taking over as Robin. Regulus is young, but you’re older, I want you to be Robin.”
Sirius broke out into a fit of laughter. “Yes, oh, yes, I would love to be Robin. Thank you, Father.”
Regulus’ jaw dropped. It was the most expression he had shown in his 9 years.