Author Note and Disclaimer: To get the formality out of the way, I don't claim ownership over any of the characters or elements that follow, those being the creation of J.K. Rowling. Their actions and personalities that differ, however, are all my idea.

My brother is the one who got me into the fan fiction scene, so if you don't like what follows, complain to him for being enabling.

I've read a ton of "Harry gets sorted into Slytherin/Harry is a fledgling dark lord" stories, but never one where Sirius didn't reject his parents' ideology and is a willing servant of Voldemort. I'm sure it's out there though, so I'm not claiming to be the first. I've talked enough, no? Let's move on to the fun. Many thanks to my beta and brother, Discordia19.

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Prologue: From Number 4 to Number 12

From his hiding spot across the street from the Muggle home, Sirius Black watched as the second greatest wizard of his age appeared at the end of the lane, drew what looked like a lighter, and extinguished every street light in the area. Sirius was torn between his desire to growl and bark, alerting the muggles to the goings on, and his desire to complete the secret mission Voldemort had given him in the event of the Dark Lord's failure to murder a one year old boy.

Black had thought it unlikely his Lord would fail, but had gone to Number 9, Privet Drive as ordered, killing the muggle family that lived there quietly and assuming his Animagus form to keep watch on the house across the street. As he watched, he realized with a start that Professor Minerva McGonagall had had the same plan, as the tabby cat he'd spotted earlier began to walk towards the fool Dumbledore.

Black crouched low in the bushes, ears perked as they talked of his fallen Dark Lord, allowing a low growl briefly when they mentioned the Potter brat, which cut off as he heard a loud screech. Flying from the sky astride a hippogriff was the oafish half-breed groundskeeper, Rubeus Hagrid. Honestly, what dolt decided on him for something so clearly hush-hush? Sirius thought with a snort while McGonagall hastily cast a silencing charm on the winged beast. Probably the old fool himself. He always did put too much faith in trash like the muggleborn, or half-breeds like the very oaf I'm looking at. He stopped his gleeful insults when he noticed the small bundle Hagrid was cradling. Cradling an awful lot like one would hold an infant. A one year old infant, one might say.

So there is the boy who defeated my master? He thought, staring at the baby the entire time while Dumbledore set him in a conjured basket and tucked a letter in next to his blankets. After a brief moment with heads bowed, the trio of Dumbledore, McGonagall, and Hagrid each left Privet Drive. Sirius stayed where he was hidden for a few minutes, waiting in case there was a trap. What lax security for their so-called savior. Are they so confident that the Dark Lord is gone forever? He wondered idly, changing back to his human form for the first time in hours and pausing to crack his back. Like any self-respecting pureblood, Black wore the finest robes available, and he paused to straighten them before striding forward with his head held high. Like his fellow Death Eater Lucius Malfoy, Sirius kept his wand hidden in a walking stick, the handle modified with a snarling dog's head to better camouflage the effect. Black crossed the lane with a few strides of his long legs and stared down at the small baby that had seemingly defeated the greatest Dark Wizard in history.

"To think they would abandon their great champion at the doorstep of some Muggle like the morning's newspaper. Even if my Lord had not asked it of me, I would be strongly tempted to spare you the fate of growing up with this kind of trash." He knelt down and picked up the sleeping infant, burning the letter and basket with a wave of his hand. The heat woke up young Harry, who giggled slightly at the soft light. "So you like fires, do you?" Sirius asked with an insane grin, putting his hand over his shoulder and motioning.

From the garage of Number 9, his motorcycle burst forth. Though Sirius hated muggles on principle, he had to admit that a few of their contraptions were amusing. Putting Harry in the crook of his arm, he kicked the bike to a start and flew into the sky, hovering over Privet Drive. From a pocket in his robes, he drew the wand of one of Dumbledore's lackeys he had defeated while in his mask, making it untraceable back to Black. "Here's a fire for you." He said, pointing the wand toward Number 4 Privet Drive. With a muttered incantation and a flick of his wrist, Sirius cast a fireball towards the Muggle home, which promptly exploded. Sirius barked a laugh as the flames began to spread to the houses next to the burning ruin. In his arm, Harry clapped and laughed, earning a smile from Black, who threw the stolen wand into the inferno. "Do you know what else is burning down there, besides the filth Dumbledore would have enslave our world? Your old life. My Lord told me to raise you as my heir, so that's what I'll be doing. Harry Potter died with his parents, and Janus Black was born from the ashes." Sirius revved the bike up to full-throttle, tearing across the sky with a roar. "Happy birthday, son." He shouted, heading towards London laughing.

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Sirius Black and his abducted new son landed easily outside Number 12 Grimmauld Place, Sirius silently shrinking the motorcycle and pocketing it as he carried "Janus" to the door, his Black family crest ring flashing briefly as it allowed him and his guest through the wards around the house. "Kreacher!" He bellowed once he'd entered the ancestral home of the Blacks. With a crack, the Black family House Elf appeared with a bow.

"Master Sirius?" He asked, his croaking voice dripping with respect.

"Has mother's health improved?" Sirius asked, hanging his travelling cloak on the wall and depositing his now wandless cane in the troll leg umbrella stand his father had carved himself.

"Kreacher is terribly sorry, Master Sirius, but Mistress is still feeling poorly. Kreacher believes she is awake, if Master Sirius wishes to speak to her." Kreacher said, still bowing so low his nose touched the floor.

"Prepare a room next to mine as a nursery, Kreacher. The Dark Lord has asked me to adopt this boy as an heir." Sirius pointed his wand at Kreacher, who looked up in fear. "You will make caring for him your prime concern. Is that understood?" He asked, knowing the threat was unnecessary.

"Of course Master Sirius, Kreacher will do as you asked. What is the new Master's name?" The elf asked, inwardly sighing as Sirius holstered his wand.

"Janus Regulus Black. Add his name to the tapestry once you have finished preparing the room." Sirius said, moving past Kreacher without waiting for a reply. "I will be in my mother's room."

Kreacher bowed low again, vanishing to follow his orders. Sirius strode up the many stairs till he reached the master bedroom, knocking politely before entering. Lying alone in the large bed was his mother, Walburga Black. Even at her age, and in the grip of an illness that Sirius expected to be her last, she still had a stern look worthy of her upbringing and blood. "Sirius." She crooned; closing the book she had been writing in and setting it aside. Her eyes widened slightly as she noticed the child in his arms. "And who is this you have with you?" She asked, eyebrow raised.

"The Dark Lord asked me to raise this child as my heir. As such, I will be legally adopting him in the morning."

Her expression clouded over as she took in his words. "I'm assuming the Dark Lord hasn't saddled you with a bastard of low birth." She said simply, waiting for him to pull a plush chair over to her side.

Sirius frowned. "The boy's blood is only slightly diluted, mother. His father's family was nearly as pure as ours, until he himself became a blood-traitor and married a Mudblood. However, under my guidance, I believe he will prove worthy of the name of Black."

Walburga sighed. "I'm assuming you have followed tradition, and removed the filth's name from the child?"

Sirius straightened his face. "Of course, mother. May I present 'Janus Regulus Black', shortly to be your grandson."

She smiled slightly. "You honor your brother still, Sirius. You were always such a good boy." She paused, as though trying to remember something. Sirius knew memories were harder for her to call up as she got on in years, and waited dutifully for her to think of it. "Your cousin came to visit with her son earlier today. Little Draco will be a valuable friend to your charge in the years to come, and his influence at Hogwarts will build on your own to stamp out the trash the boy comes from."

Sirius nodded and opened his mouth to speak when Janus yawned and fell asleep. "It would appear the night has been most exhausting for Janus." He leaned over and kissed his mother gently on the forehead. "And you should be resting as well, mother. I will see if Kreacher has completed the nursery, and then go to my study to begin drawing up the paperwork to legally claim the boy."

Walburga bade her eldest son goodnight, smiling slightly at the small child in his arms as he walked out of the room.

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After a quick detour to put Janus in his new crib, and reminding Kreacher that he was to be awake as long as Janus was asleep, Sirius sat down at his large ebony desk to draw up adoption papers. With enough bribery to the right people, Sirius knew that Janus wouldn't be considered an orphan Sirius had adopted, but his own son.

In fact, I believe there's something that can help with that. He thought, going into a side room of his study, where he had a magical safe that could almost rival Gringotts in terms of protection. Pulling out a book on dark potions he had gotten from his old head of house Horace Slughorn on the pretense of needing to know how they were made so he could prepare antidotes, he apparated to the basement, where he and Regulus had continued their practice with potions brewing. Reading the instructions by torchlight, Sirius waved his hand absently, summoning the necessary ingredients.

This potion takes roughly six hours to brew. He thought; pulling out the pocket watch his parents had gotten him when he became of age and checking the time. I had hoped to finish it before taking Janus with me to Gringotts. Sirius sighed, lamenting again the loss of his brother. With two people working, it would have taken much less time to prepare the potion. Sirius snapped the book closed, realizing there was someone who could help. If Sirius could be said to have friends, then Severus Snape was his best.

Disapparating back to the main floor, he strode to the fireplace and cast floo powder in, before sticking his head through. "Severus!" He called, looking around the potions master's office. Just as he was about to curse and try to contact someone else, the door burst open and Snape began flinging curses around the office, destroying several empty phials. "Severus!" He barked, catching the attention of the furious potions master.

Snape stared at the head of Sirius Black in his fireplace, a look of momentary panic on his face as the sight of a Death Eater cut through his grief over the death of Lily Potter. He quickly composed himself and straightened up. "Sirius, my friend. Is it true? Has the Dark Lord fallen?"

Sirius nodded grimly, the cause of Severus' rage becoming apparent. "I am afraid so, Severus. I understand you're angry, but could you come through the floo? I need your expert assistance with a potion that must be completed before daybreak."

Snape looked at his "friend" with a puzzled expression. On the night of his master's defeat, Black was preoccupied with brewing a potion? Perhaps it's something he thinks would resurrect Voldemort? At the very least I should go through and investigate. "Of course, Sirius." He said, stepping through the flames and arriving in the Black home. Sirius obviously doesn't feel he's in any danger of being discovered as a willing Death Eater if he isn't in hiding. "What potion do you need done by daybreak?" He asked once they'd apparated to Sirius' hidden laboratory. Sirius summoned the book he was working from, which opened to the exact page on its own. Snape raised an eyebrow, his suspicion now replaced with curiosity.

"With my help, can you have it done in a few hours?" Sirius asked with a hopeful expression. Without answering, Snape began to work on preparing the potion. Brewing always calmed him down, and the tragedy his life had become would hopefully be alleviated after a few hours of work. Snape grimaced as he remembered what he had agreed to do, protecting the son of his enemy, the thief of his heart's desire. Not that he could tell Sirius that. Ever since they had first met at Hogwarts, Sirius had tried to dissuade Snape from courting Lily and insisted he instead court one of Sirius' endless supply of cousins. It still made Snape shudder to think of being married to Bellatrix, the insane witch who some of the braver Hogwarts students had asked Sirius if he was going to marry.

"I can have the potion finished in four hours without your help, Sirius. Is that satisfactory?" Snape asked, inwardly shuddering at the memory of what had happened to the brave when they had mocked Sirius. Like when he transfigured Frank Longbottom's leg into tree roots. He still walks with a limp from that.

Sirius, unaware of the line of Snape's thinking, nodded with a grin. "Excellent, my friend! I'll leave you to it, while I go finish writing the adoption papers."

Snape's eyes widened, but with his back to Black, he looked as though he was merely continuing to work. "What lucky child is being adopted into the great house of Black?" He asked casually, the reasoning for Black needing this potion becoming clear. I'm sure it's the child of a deceased Death Eater. Maybe Macnair finally got himself killed, or Moody took down Dolohov.

Sirius frowned, wondering if Snape was to be told. Deciding it would be best not to tell his friend, he snorted derisively. "All I'll say is a certain pureblood produced a filthy half-blood, and offered it to me as an heir apparent until I have a child of my own." He spat theatrically. "I considered cursing him for the insult, but decided having an older brother who seemed conditioned to be the head of house would push my actual son to succeed even harder."

Snape nodded, bored as always with Black's fanatical devotion to blood-status. With the exception of Snape, none of the Death Eaters knew their master was a half-blood himself. And as for Black's plan…It certainly didn't make Regulus any more impressive a wizard. Snape thought, knowing he would never in his life tell Sirius.

Black was convinced of his family's superiority over all others, and was especially touchy when it came to his deceased brother. He had been told Regulus had been ambushed by the members of the Order of the Phoenix, and ever since then was especially merciless on the battlefield. In fact, Sirius had been pushing for an all out invasion of Hogwarts, so he could find the children of those Gryffindors he suspected had killed his cherished younger brother. He had settled for leading the majority of raids against the muggleborn, knowing that when they had gained enough followers, the next target must surely be Dumbledore.

Snape grimaced again at the thought of the brutality of the man who called him friend, and returned to brewing the potion that would make the child he wanted to raise his son in blood.

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That morning, Sirius Black and a baby with magically altered eyes and a small cap over his scar strode into Gringotts, the wizard bank. Sirius was rather glad it was November, so covering the child's head was not only responsible, but expected.

After presenting the necessary paperwork claiming that the child was the son of a distant cousin of Sirius', (which was probably technically true, now that Black thought about it) explaining that the boy hadn't been put down for Hogwarts yet because his parents had been in hiding from Death Eaters, and granting him eventual access to the family vault, Sirius decided to set up a side-vault of galleons for the child's schooling. Sirius transferred one hundred thousand of the gold coins, figuring that would be enough spending money to last the boy once he was enrolled in Hogwarts.

Another quick stop in Knockturn Alley to commission another Black family signet ring for his young heir and meet with certain contacts to pave the way for Janus being considered Black's son by birth, Sirius returned to his home to find his cousin Bella, her husband Rudolphus Lestrange, and young Barty Crouch Junior waiting for him in the lobby. After ordering Kreacher to feed Janus and put him to bed, Sirius turned to the assortment of Death Eaters. "Cousin Bella, Rudolphus. How can I help you?"

Bella paced in the lobby like a cat, practically sobbing in her frustration. "Sirius, our Lord has fallen, just as he warned us he might! There has been no word from many of our comrades, who I feel will abandon him now that he seems weakened. What should we do?"

Sirius paused, thinking back on what Voldemort had said before leaving for Godric's Hollow. After a short time, his expression grew firm. "The Dark Lord gave me a task to complete in the event of this happening. I have already begun it. Did he give you similar orders?"

Bella and Rudolphus nodded immediately, while Crouch took a few seconds before nodding as well. "We are to get ourselves imprisoned in Azkaban, and feed our hatred to the Dementors. When the Dark Lord rises, he will promise them sweeter emotions from the blood-traitors and muggles." Bellatrix said, head held high with pride in her being given an important duty.

Crouch cleared his throat, clearly hesitant to speak his job aloud. "I am to put my mother under the Imperius curse, so she will help me "die", leaving me better able to set the framework for the Dark Lord's eventual return."

Sirius nodded with a grim smile on his face. "It would seem that our Lord has made many plans to be enacted later." His smile turned insane, as it always did when he knew there was murder to be done. "Now then, you are to be imprisoned. It seems to me there are two ways to accomplish that. You can either surrender to the Aurors…" He began, raising a hand when Bella began to interrupt. "Or you can go to the home of two of their number, Frank and Alice Longbottom, and rob the muggle-loving fools of powerful servants." He said, his grin now baring teeth with his eyes flashing maniacally.

The three laughed at the prospect, Crouch's smile rivaling Sirius' in its intensity. "They'll be useless to the Light side within the week, my dear cousin." Bellatrix swore, putting on her travelling cloak and making for the door, followed by the other two. She paused at the threshold while her husband moved past her. "Give my regards to poor aunt Walburga, Sirius." She said solemnly, apparating off the front porch with a twist.

"Until I see you again, Bella." Sirius said solemnly, thinking of the toll the Dark Lord's plans were taking on the Black family. He shook his head free from the treasonous thought, endeavoring to set up a reasonable alibi for the next week to avoid his own incarceration. After all, he had a son to care for now.

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Dumbledore sat happily in his office, excitement building for the day when young Harry would arrive at Hogwarts. The devices behind his desk, tuned to the wards that had gone up at six that very morning at Number 4 Privet Drive, remained quiet, indicating that the boy had been taken in by his aunt and uncle, just as he'd planned. Dumbledore wasn't aware yet, though he would be within the week, that his wards were protecting a burned husk of a home. Thanks to the machinations of Lord Voldemort and his faithful servant Sirius Black, Albus Dumbledore would never knowingly lay eyes on Harry Potter.

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Endnote: Well, this is quite the AU, isn't it? With Voldemort being intelligent and all. The next chapter of Serpent's Son will show Janus' eleventh birthday, where he'll get some happy wishes from an unexpected source.

By the way, for those of you wondering about the name change: the Black family obviously has an astrology fetish when it comes to naming their children, and Harry will be two-faced in this story. Obviously, Janus isn't a constellation, but the only overlap I could find was 'Pisces', which I just couldn't take seriously as a name.

Please Review, as I'd like to have more than my brother telling me I'm a decent writer.