It was 1977. Night time animals frolicked, the moon was shining in the sky, and at 12 Grimmauld place, London, the Black household was preparing to receive their guests. It was yet again time for the annual Black family reunion, and that could only mean bad news for fifteen year old Sirius Black.
6:10PM
Sirius was in his bedroom, standing in front of the mirror and tugging at his collar. The dress robes his mother had forced him into were designer, and very uncomfortable.
"Sirius and Regulus!" His dear mother screeched, calling for them to come downstairs. He could hear his younger brother's hasty footsteps and his door banging shut. If he went any faster he might have fallen down the stairs. Sirius rolled his eyes. Regulus could be such a suck up.
"Sirius!" Walburga Black screamed again. He ignored her. Sirius' eyes roved over his bedroom walls, scanning the very familiar posters of bikini clad muggle women, motorcycles and the oversized Griffindor banner all permanently stuck to the wall. These items covered the disgusting wallpaper, and also annoyed the hell out of his parents. His eyes lingered on the photograph on the wall of he and the other marauders. Idly, he wondered how they were doing. It occurred to him that he should write to them, but he had this reunion to survive first.
Sirius then made the wise decision to start going down the stairs. The dress robes he was wearing were plain black with a silver clasp, a storm grey tie, and a crisp white dress shirt. It looked really good, and he had even brushed his hair to rid it of tangles, but it was possibly the most uncomfortable thing he had ever had the misfortune of putting on, besides, Sirius didn't enjoy looking so upper class. He much preferred jeans and a leather jacket. He reached the top of the stairs and was about to descend just as his mother stuck her head around the corner. She shot him daggers with her eyes, and told him,
"Hurry! They will arrive soon." And then she disappeared back into the kitchen.
The walls at 12 Grimmauld place were all a sickly green, and ornamental snakes decorated the place. Every person in his family had been sorted into Slytherin house, but Sirius was a Griffindor, much to the disapproval of his pretentious mother. Oh, the howler he got when she found out! On the final landing before the ground floor there hung the heads of long deceased house elfs on a wooden plaque. Sirius cringed at the sight of their shriveled little heads and blank eyes as he passed.
Finally, Sirius made it to the bottom floor and strolled towards the kitchen, dodging the troll leg umbrella stand. Regulus was wearing similar attire to him, and was sitting up very straight in his chair at the kitchen table when he entered.
"You're here. Finally." Their mother rolled her eyes. "Now I wanted to remind you two of what is expected. You should be polite, and greet each of our guests personally. As their hosts I expect full responsibility out of both of you." Walburga Black shot Sirius a pointed look.
"Now remember what I told you about greeting Caelum and Matilda. You're to be on your best behavior." Once again Sirius was shot a look by the woman.
"Mother?"
"Yes Regulus dear?" She replied joyously.
"They have children, do they not?"
"Yes dear, two daughters and a son. Their names are Ceti, Carina and Arcturus."
"Very nice names."
"Yes, indeed. Very traditional And they are pureblood, too. Matilda's maiden name is Gamp." Walburga nodded, smiling. Sirius honestly didn't give a damn about any of their relations, nor did he believe that purity of blood is what made a person worth hanging around. Ever since his cousin Andromeda was disowned for marrying a muggleborn, these family gatherings had become all the more dry, if that was even possible.
"How old are they mother?" Regulus was still going on.
"Ceti is ten, just about to start Hogwarts. Another proud Slytherin for our family! And Carina is thirteen going on fourteen, and Arcturus would be in Sirius' year."
"So Arcturus is fifteen?" Regulus concluded,
"Yes, he is. Oh goodness, it's been so long since I saw them! Sirius and Arcturus were only toddlers then!" Walburga smiled nostalgically at her youngest son. Sirius meanwhile, was leaning carelessly against the door frame and trying to tune them out. His mind was on that letter he should be writing to the other marauders right now.
The doorbell rang, and his mother trotted away to answer it.
"You okay Sirius?" Regulus questioned.
"These robes are uncomfortable." Was all he said, and then he walked away. He made his way up the staircase again to the drawing room, and sat himself down in front of the Black family tree tapestry that spanned across the wall. His eyes wandered across it, not really taking in the details on it. His mind was elsewhere. Downstairs, he could hear a few more guests arriving, who he was supposed to greet, but he stayed where he was. He didn't feel like pretending to be nice. And what of these newfound Blacks? As if they needed more self righteous pureblood freaks hanging around. He wondered idly why he hadn't seen this Arcturus guy around Hogwarts. He may be a Slytherin, but he hadn't seen anyone even remotely resembling a Black who he didn't already know was a Black. They were supposed to be British, so why weren't they at Hogwarts?...
Oh whatever. Sirius didn't even care. What he needed was a good prank that would last the duration of the reunion, and he had a perfect idea- he would prank this Arcturus guy.
Yeah, that would really make his mother lose it.
With a sly smirk, he rose from where he sat. His cousin would be arriving shortly.
6:26PM
Sirius shook the hand of yet another Black relative.
"You're chirpy today Sirius." Commented his aunt as she took another sip of firewhisky from one of the silver goblets with the Black family crest emblazoned upon it. She looked almost like she thought he was acting suspiciously.
"Always good to see ya." Sirius grinned. She shot him one more odd glance, and then toddled away, probably to go talk to one of his other aunts about blood purity and family ties. People he didn't recognise suddenly apparated on the street outside. This must be the new cousins and aunt and uncle. Carefully, Sirius slipped his wand out of his pocket and waited. There was a child, two teenagers, and their parents. Each of them had the black hair and pale creamy skin that was so common in the Black family. He could bet almost anything that they all had black or grey eyes, too.
The only exception to these features was the mother, whose blonde hair and blue eyes were obvious among the other members of her family even from halfway across the road. They quickly approached him, and he shook first the father's hand and hugged the mother and two girls.
"I am Caelum, this is my wife Matilda, and my two daughters Ceti and Carina." He introduced, then he gestured to the curly, long haired, and suprisingly blue-eyed teenager. "and my son-" he began to say,
"Arcturus." Arcturus said, and stuck out his hand for a shake. Sirius opened his mouth,
"Sirius." He meant to respond, but nothing came out. He mouthed his name again, but again, it wasn't audible. Arcturus cracked up laughing at his open mouthed, confused expression. Sirius closed his mouth, frowning.
Arcturus had pranked him!
"Arcturus. We spoke about this." Matilda said tightly. She waved her wand, and Sirius had his voice back. He had used non-verbal magic.
"I didn't hear you say the spell, how did you do that?" Sirius asked Arcturus.
"I mumbled it while dad was busy telling you our names." He shrugged. Oh. Very sneaky. Sirius could tell just by the way he looked and spoke that he would be popular with the girls. Plus the prank playing... Arcturus was competition. That was why, as the new arrivals filed into the house, Sirius shot a spell at the back of Arcturus' curly haired head. That would give him a nice, shiny bald patch. He laughed to himself, and leaned against the doorframe to wait for more guests.

Author's note
Thanks for the read, dudes hope you like it :D