You hurt him, you pay.
“GIVE IT BACK YOU LITTLE BRAT!” Regulus heard his oldest cousin Bella shriek, most likely at his brother, and two pairs of feet stomping up the stairs. The two of them had never gotten along even though they are so similar…maybe it's because they are so similar that they don't get along. It certainly hasn't helped that Sirius loves poking fun at the teenaged girl, constantly provoking her to get a reaction.
“Come and get it Bella!” His brother sings, he could picture the devilish smirk on his brother's face. Regulus let out a sigh too big for a five year old and put his book down to go see so that Bella doesn't murder his brother, behind him he could hear Andy following him.
“Does he have to provoke her every single time?” Andy groaned.
“You have met Sirius right?” Regulus asked in a black voice, glancing back at her, Andy let out a tired chuckle and nodded her head. Their siblings were still screaming at each other as they came up on them. From where they were standing they could only see a little of Sirius face as Bellas back was facing them, she was looking down at his brother and holding out her hand at Sirius to hand over whatever he took.
“What's the magic word?” Sirius asked in a teasing voice, fully knowing that Bella would rather shave off all her hair than say ´please´. It seemed that this was the teenager's last straw, her shoulders tightened, and even though they couldn't see her face they could guess what expression she was currently making as Sirius´ cheeky smirk fell and his eyes widened. Andy took a step forward, clearly sensing that she needed to intervene or something might happen.
“Come on Bell-” She never finished her sentence as Bella raised her arms and pushed Sirius backwards, right over the edge of the stairs. Everything slowed down, Regulus met his brother's eyes and saw the terror in the silver. Sirius cried out when he made contact with the hard stairs, not being able to stop his momentum as he continued tumbling down. It seemed like the fall went on forever, but when Sirius finally came to the end of the staircase he was silent. Andy was frozen for just a second but then she flew down the stairs after her cousin, shouting at him to wake up. But Regulus couldn't hear her, he was staring at Bellatrix in rage, glaring at her with a glare that would make his mother proud. She was smirking, she was smirking.
Regulus wanted her to hurt.
He needs her to suffer.
It was as if someone heard his thoughts, because suddenly she was on fire. The girl started screaming in pain, flailing her limbs in an attempt to put the fire out. Regulus just watched on with an impassive face, visibly not caring that his cousin was hurting.
You hurt him, you pay.
Bellatrix runs past him and into a bathroom where he can hear the shower turning on, with one last look down the hall he walk to the stair and hurried down to the bottom where Andy was healing his brother to the beast of her abilities, seeing as she is only fourteen she is doing a remarkable good job. He falls to his knees next to his unconscious brother and takes his hand in both of his small ones, he looks up at his cousin and askes in a wobbly voice,
“Is he going to be okay?” She glances at him and her eyes soften as she takes in his red-rimmed eyes, “Yeah Reggie, he's going to be fine. He has a thick skull.” She winked at the five year old, making him let out a wet giggle.
“I know that I should probably be angry at you for setting my sister on fire, even if it was accidental magic, but to be honest she deserved it.” Regulus nods his head, not even a little bit apologetic about what he did, she hurt his brother so he hurt her, it's a fair trade. Andy reaches over and strokes his hair, nodding down at his brother, “We should get him to be so that he can rest.”
He nods his head and reluctantly lets go of the warm hand between his cold ones, Andy carefully scopes up the seven year old and hold him in a gentle grip, Sirius arm dangle free and so Regulus quickly takes a hold of it again, not very found of the idea of being apart from his brother.
“You sat her on fire?!” Sirius whisper-shouted, staring at him with wide unbelieving eyes. Regulus met his brother's eyes and shrugged, “She deserved it.” He said in an unbothered tone.
“Well- yeah obviously but…what?” That was unusual, Sirius doesn't usually become speechless, he could probably count the number of times it has happened on one hand, and have fingers over.
“Kinda proud of that one actually.” The more Regulus talked the wider his brother's eye became. He is genuinely starting to worry that he is having a stroke.
“Are you having a stroke?” Never hurts to check. Sirius flounders, his mouth opening and closing, not terribly unlike a fish.
“That was your first accidental magic?” Regulus looks down at the question, making eye contact with warm brown eyes, Potter. He looks curious but mostly impressed for some reason.
“Yes?”
“Bloody hell, first time doing magic and you set your cousin on fire.” The older boy let out a breathless chuckle, looking at him with an expression that Regulus has never seen before,...well that's not entirely true when he thinks about it. Potter has always been weird, sure, but the few times the two of them have interacted he´s even stranger, but he has alway had that look in his face. Regulus has never really thought about it and he doesn't really want to start now, so that little revelation is going inside a box and shoved deep, deep down.
He looks away from Potter and turns to his brother, who has finally overcome his momental laps in brain function, and has now joined the land of the living again. Though he isn't looking at him, no, he is glaring where Regulus was looking moments before, outrage clear on his face. But that makes no sense, why would he be glaring daggers at Potter, they are best friends, practically brothers, Regulus thought with not a small amount of contempt. Suddenly not caring why Sirius looked like he would like to erase his best friend's existence. He glanced down at Potter once again, taking in his panicked expression and relishing in it.
“Prongs…” His brother said in a calm, dangerous voice.
“Yes, Padfoot?” Potter said in an anxious voice, sending Sirius a shaky grin, his hand coming up to run through his already messy hair.
“We are going to have a talk as soon as this is done.” Sirius said in a deadly tone. Potter bleaches and quickly nods his head.
Seeming pleased Sirius turns away from his best friend and faces the screen once again, avoiding Regulus' curious glances.