"Regulus Orion Bla—" Severus paused, cursing himself inwardly. "Regulus Orion Snape! Come back here this instant!"

Sirius laughed and ran off toward the castle. "Bet you can't catch me!"

"Oh, I will, young man. And when I do, you will be over my knee!"

"Come on, Sna—I mean, Daddy. Let's race to see who can get to Hogwarts first."

"Oi, Prof'sser Snape!" Hagrid called out, coming toward him. "Is that the tyke Prof'sser Dumbledore said was comin'?"

Severus sighed, rubbing his eyes. "Of course, he told you all ahead of time. Why wouldn't he? It's not like it's my child and my secret." The man nodded. "Yes, this is my son, Regulus."

Sirius ran over and stood next to Severus's side. He waved. "Hi, I'm Regulus Orion Snape. I am the son of two death eaters, but one of them died because she couldn't keep herself away from the business end of a bottle."

Hagrid frowned. "Poor lad." He shook his head. "Precocious li'l fella, ain't he?"

"Yes," the potion master ground out. "One that needs to find a more appropriate way to introduce himself."

"Is he really only four?"

"That is what his birth certificate says."

"Don't that mean he will be comin' to school the same time as 'Arry Potter?"

"It would, wouldn't it?"

"Crazy, you and Lily havin' kids at about the same time."

"At least one of us knew we were having children," Severus said, looking down at the boy with disdain. "I do believe it is about time for someone's nap. Good day, Hagrid."

"I am not taking a nap," Sirius said, following Severus and their luggage toward the potion master's quarters.

"That's what you've said every day for the past two months," Severus said, opening the door. "And yet, every day, at this time, I've found you in random places, asleep."

"I'm twenty-four. I do not need a nap."

"Your body is four and it does need a nap."

"I'll scream. And then everyone will come running and think you were hurting me."

"And then I'll tell them you were having a tantrum because you refused to take a nap, and they'll believe me because I'm the adult."

"You're mean."

"And you're intolerable." Severus marched over to the newest addition to his suite. "This is your room. Dumbledore made sure it fit with being the son of the head of Slytherin."

Sirius scrunched his nose. "No."

"Yes." Severus opened the door, revealing a green and silver themed room. The walls were painted with a Quidditch field, and there were players flying around.

"At least it's Quidditch themed."

"It also contains a bookshelf, which shall hold books considered age-appropriate."

"You mean, no Playboys?"

"How do you even know what those are? They are purely muggle in nature," Severus said, grumbling. "I should know. Scarred me when I came across my father's."

"Jamie introduced me."

"How would he know?"

"He spent a lot of time in Muggle London."

"Anyway," Severus shook his head, "as the precocious son of a potion master, you will be expected to excel at potions." He handed over several tomes, mostly containing pretty pictures of potions ingredients.

"I was an auror. I had to get an O on my N.E.W.T." Sirius reminded him, scowling.

"Yes, but how will we explain your immense knowledge of potions?"

"Point made." The boy grabbed the books and looked at the covers. "One Hundred Potions to Make with Your Kids? Seriously?"

"Remus found it and thought it would sell the act."

"Can we do one?"

"Nap. Now."

Sirius grumbled and sat on his bed. Within minutes, he was fast asleep. Severus sighed and went over to the floo, inviting Lucius and Remus to his flat.

"How's Harry?" Severus asked, pouring tea for his friends.

"Good. He misses Sirius, but I explained that he had to go away and that now his younger brother Regulus would take his place," Remus said, grabbing a biscuit.

"Do you think we'll ever actually explain that Sirius and Regulus are the same person?" Lucius asked.

"We probably will have to eventually."

"If I don't kill the boy first," Severus said, grimacing.

"What did he do now?" Remus moaned.

"He needs to learn to talk like a four-year-old."

"You can't just pass him off as very bright?"

"What four-year-old knows about the business end of a bottle?"

Remus nodded. "I'll talk to him."

"After he finishes his nap."

"You finally convinced him to take a nap?"

"He takes one anyway. I just finally convinced him a bed is softer than the kitchen floor."

"Draco's going through that stage, too," Lucius said, shaking his head. "He refuses to take a nap and Narcissa actually listens to him."

"Harry seems to enjoy his naps, still." Remus shrugged. "I guess it's a nice alternative when living with Petunia Dursley."

"Don't you still have nap time when you teach them?"

"Yes, but Draco does tend to figure out how to unlock the door and escape."

"Isn't this the same boy that was scared to death of doors?" Severus asked, smirking.

"He wasn't scared of them," Lucius huffed. "He was just sad that they were shut."

"My version is better when told at a wedding."

"Maybe Sirius would benefit from preschool," Remus said, taking another biscuit. "That way, you don't have to worry about him being unattended."

"I already plan for him to do some schoolwork at the front of my classroom while I teach," Severus said with a wave of his hand.

"Any child would become bored with that, especially Sirius! He'll become a nuisance to your classroom."

"Not if he wants biscuits with his tea."

"Oi, this is going to end very badly," Remus said, rubbing his eyes.

"He has a twenty-four-year-old mind. What could he possibly need to learn?" Lucius asked, scowling.

"Considering the fact that he never attended a muggle school?" Severus said, shrugging. "I have planned for him to learn muggle math, history, and science."

"And you honestly think he'll sit there and do his work?" Remus asked, throwing his hands in the air. "You remember Sirius from school, don't you? You took classes with him!"

"He just never had a stern hand guiding him toward acceptable behavior."

"One of you is going to end up dead."

"And then I will no longer have to care for one Regulus Orion Snape."

"Or he'll be an orphan," the lycanthrope pointed out, taking another biscuit.

"Do you really think he'd best me? Ever?"

"No, I think you'd best yourself."

"Enough!" Lucius said, glaring at his two friends. "This is ridiculous. Why don't you plan on having him three days a week, Remus, and the other two can be spent with Severus?"

"Did you just work out a custody agreement?" Severus asked, crossing his arms.

"Yes, because apparently you need one." Lucius rubbed his eyes.

"Remus will be too soft on him!"

The man in question huffed. "He's a child, Severus, not a soldier or prisoner of war."

"Oh, but that's where you're wrong…"

"Again, both of you!" Lucius slammed down his tumbler. "This is not going to help him have a decent childhood. Severus, you can have your structure, but you must at least pretend to like your son and treat him fairly."

"Why?" the potion master asked, brow quirked.

"Because that's what parents do."

"You pretend to like Draco?"

"I actually do like him, but I'm not expecting miracles." The blond turned to Remus. "You will go along with Severus's expectations and rules. It's important that you set up a united front and keep a continuity that Sirius can learn and feel safe in."

"What if he makes totally inappropriate and unreasonable expectations?" Remus asked, glaring.

"That's where I come in," Lucius said, eyes sparkling. "As you both know, I am the only one here with experience in child-rearing. I will make sure he does not create a hostile environment for the lad."

"Fine," the lycanthrope sighed. He turned to Severus. "Where do you plan on starting with him in math?"

"Calculus," Severus said grabbing some sugar.

"But he has no prior knowledge in higher-order mathematics! Half of that isn't even numbers!"

"Which is why your preschool may in fact come in handy."

"I'm teaching them to count and add one-digit numbers, not how to find the angles of a non-standard triangle!"

"How do you know so much about trigonometry?" Severus asked, mouth dropping.

"I like to read and there's very little to do during nap time." Remus sighed. "Why don't you start him on pre-algebra? He's at about that level considering his prior education."

Severus huffed. "I guess that will work for now." He cocked his head. "I guess he would hit calculus before time to start Hogwarts."

"What is this obsession with calculus?"

"I have a four-year-old with the mind of a twenty-four-year-old. I am creating the world's brightest child."

Lucius turned to the werewolf. "Why did you have to say it was Severus's son again?"

"I'm starting to wonder that myself," Remus replied. He turned back to the potion master. "Repeat after me: Sirius is a child and not an experiment."

"Black is a child and an experiment," the potion master said, rolling his eyes.

"I think that's the best you'll get from him," Lucius said the lycanthrope.

At that moment, Sirius rushed out if his room. "Moony!" he called and jumped into his friend's arms.

"Sirius!" the man cried out, coughing. "This isn't getting less strange. I thought it would with time."

"Moony, I'm so glad you're here! I was missing you lots and lots."

"You saw me a few hours ago."

"And it was torture being apart for those few hours," Sirius said, smirking. He transformed into Padfoot, the puppy barking and wagging its tail.

"Now, how could you ever be angry at that fluff-ball?" Lucius asked, picking up the pup and scratching his ears.

"Did you wake up to all of your underwear frozen?" Severus asked, glaring.

"Well, no…"

"Then you have no room to ask me that."

"You have to admit," Remus scratched his chin, "he would have done that whether or not he was four-years-old." He shook his head. "What interests me is that he's still an animagus."

"And he's a good boy," Lucius said, now moving to scratch his back.

"Lucius, you do not need a dog," Severus huffed, grabbing his "son" and setting him on the floor. "One-hundred thirty peacocks is enough."

"One-hundred thirty-five, thank you very much."

"You bought five more?"

"They were on sale."

"Lucius the animal lover, everyone," Remus said, motioning toward the blond. "What did Narcissa say when you told her?"

"Who says I told her?"

Severus shook his head. "Remus, prepare the couch for Lucius. He's going to need it."

"Why can't I just use one of my other hundred rooms?"

"Because when your wife finds out what you did, you will find them all permanently locked."

Padfoot turned back into Sirius. "Ooh, is that firewhiskey?" He went to grab some from Lucius.

"Ah, ah, ah! No alcohol for minors," Severus said, pushing the boy away from the tumbler.

"But I'm not a minor."

"Your body is, and it does not need alcohol."

"But my mind is twenty-four, and it really wants alcohol."

"What if Dumbledore were to walk in and find my four-year-old drinking firewhiskey?"

"Knowing him, he'd join."

Lucius ran a hand through his hair. "Why do we have this man as the headmaster of a school?"

"I feel like Lily asked that several times. Especially after the mariachi-band incident," Remus said. "He started the cha-cha line."

"And didn't he participate in Jello-wrestling?" Sirius asked, brow quirked.

"He told me last year that if teachers act like it's no big-deal that a student did something, the student is less likely to do it again," Severus said, shrugging. "Many times, they do things just to get a reaction from the professor."

"Well, obviously we do things to mess with the professors," Sirius said, crossing his arms. "But we also do things just because they're fun and to see if we can actually do them."

"A prime example being when they tried to jump out of the astronomy tower," Remus said, shaking his head.

"And to answer an obvious question: no, you actually can't. They set-up wards."

"That was not the question I was going to ask," Severus said, rubbing his eyes. He turned to his friend. "Why didn't you stop them?"

"Have you tried stopping James and Sirius when they have a question they need answered?" Remus shook his head. "They are impossible."

"Especially when we put a body-bind on Moony," Sirius said with a giggle.

"That's another question I need answered: can Black still perform magic as well as he did before?" Severus asked, rubbing his chin.

"Well, he's still an animagus," Remus pointed out, and Sirius turned into Padfoot.

"But his magical age is four, according to the spell," Lucius said, patting the couch for Padfoot. The pup wiggled his butt and made the leap, but missed the mark and fell back onto the floor.

"If we're done," Severus said, looking disapprovingly at the pup. "I think it would be reasonable to test and see his current limits. Would you two not agree?"

"With some parameters?" Lucius asked. The potions professor nodded. "Then yes."

"We could use Harry and Draco as controls," Remus said, his eyes lighting up. "And then we can make a spreadsheet and chart their overall growth."

"Weren't you just opposed to using a child as an experiment?" Severus asked glaring.

"I actually like Sirius, so I know I won't cause him any harm." The lycanthrope bounced in his seat. "And we can compare their data with the data from the ministry on underage accidental magic…"

"That exists?" Lucius asked, brow furrowed.

"If it doesn't, it should," Severus mumbled.

"With as bureaucratic as our government is, you don't think it has everything recorded in triplicate?" Remus asked, gathering some parchment. "What should be our first test?"

"Ah, a test?" Sirius asked, popping out of Padfoot form.

"We could make it a duel," Lucius said, taking another sip of firewhisky. "How do we know the ministry won't detect the underage magic?"

"We'll do it here at Hogwarts," Severus explained, going over to his bookcase and pulling out several texts. "As a professor here, I have access to several newer studies on young wizarding development we can use to see whether our theories are correct concerning Black's magic levels."

"Can I see a copy?" Remus asked, reading over the other man's shoulder.

"So, wait, are we actually making a study?" Lucius asked, brow furrowed.

"And I'm the test subject!" Sirius whined.

"I don't think we can ever publish it without admitting to several felonies," Severus said, crossing his arms, completely ignoring the boy.

"Most of which you committed," Sirius pointed out.

"And no study is worth its salt with only three samples," Remus said, off-handedly.

"Yes, admittedly our sample is already skewed."

Sirius waved his hands in the air. "Uhm, did everyone miss the fact I just accused Snape of multiple felonies?"

"Shall we bring the boys over now?" Lucius asked, standing up slowly.

Remus and Severus sat side-by-side, pouring over the most recent study. The potions master glanced up. "Oh, yes, that would be helpful. Why don't you go get the children while Remus and I design the experiment?"

"Without my input?"

"What sort of input do you think you can offer?"

"Hey, you just dissed my cousin!" Sirius said. "I mean, I agree, but…"

Lucius rolled his eyes. "Fine. My lowly mind will go grab the boys while you two braniacs do all the heavy-lifting." He lowered his voice. "It's not like I haven't completely manipulated the wizarding world to stay out of jail or convinced the dark lord that I am still loyal after…." He walked away, mumbling about his great intelligence to himself.

Remus's eyes looked over at the empty spot. "Did Lucius just admit to talking to Voldemort recently?"

"I do believe he did, Moony," Sirius said, sitting down.

"No, I believe that he's referencing the moment he realized he didn't want to be a death eater anymore…" Severus glanced up. "It was right after Draco was born and the dark lord forced Lucius to torture a muggle child to death." The potions master shrugged, turning back to another study. "I didn't even know about it until last year."

"Well, should we talk to him about it?"

Sirius nodded. "We should definitely talk to him about it."

"Did he offer that information to you?"

"No." Remus and Sirius said together.

"Then keep your mouth shut and start writing out parameters." The potions master turned to the young child. "You, go and read a book."

Sirius scowled. "Why is that your answer to everything?"

"Because books keep you quiet."

"Not if I read aloud."

Remus sighed. "Sirius, do not annoy your adoptive father." He turned to Snape. "Do you know what a normal four-year-old should be able to do magically?"

"No, but I know where a study is that charted the growth of magic over time in fifty average magical children…"

"Look who came straight from naptime," Lucius said, carrying two sleepy little boys. "Narcissa's not happy I woke them up."

"You could have waited until they woke up naturally," Remus said.

"Yes, tiredness will only skew the results further," Severus mumbled, scowling as he did some math on a parchment.

"Go lay them down in Sirius's room before we have several temper tantrums on our hands."

"You don't think they'll be that bad, do you?" Lucius asked.

"Oh, I didn't tell you about the time Draco refused to take a nap and kept throwing Cluedo pieces at Harry, keeping him awake, causing him to melt down as I took him back to Petunia's?" Remus asked, looking up. "Only to come back and find Draco asleep upside-down on the stairs."

Severus smirked. "Was there a locked door involved?"

"I should have locked the door," the lycanthrope shrugged. "It would have made for a much more peaceful afternoon."

"So, grand experimenters. Tell me your plans," Lucius said, coming back in childless.

"We need to gauge what exactly a four-year-old should be able to do," Remus started, looking over at the boy-in-question. "Then we see what Sirius can do."

"Well, two precocious boys may be a start, but I highly doubt we can use them alone as a fair comparison," Severus said, staring at his parchment.

"Do you have a stockpile of four-year-olds I don't know about?" Remus asked, brow quirked.

"No, but I know someone who does."