Tom Riddle was truly one of a kind - cleverer, better-looking, more well-spoken than everybody else, but all these things had merely put him above the Muggles. Tom Riddle had always been extraordinary, even for a wizard. If anybody could conquer death, it was him. Tom Riddle had long ago put two and two together - the gods the non-magical used to worship were simply wizards, wizards who had walked among them before the Statute of Secrecy was enacted. But wizards had given up on their power, or refused to use it. Wizardkind had embraced mediocrity in the interest of protecting Muggles and children of Muggles. It was not surprising to learn that Slytherin had ultimately left the school that he had founded, and in Tom's opinion, it showed. Tom knew exactly who would restore the wizards' rightful place - him, king among kings, and when he gained immortality, he would become a god. But such ideas were not presentable to polite society - "do I look a murderer to you?" Professor Slughorn had asked him, shocked, forgetting that only those who were going to die had any need to protect their soul. Slughorn, who was willing to break the law of man for candied pineapple, would not break the law of nature and magic for immortality and domination. Such was the state of the Slytherin House. Tom Riddle was obsessed with the future - he was adamant that he would not miss a second of it, he would live forever - but the past was equally important, and it belonged to him as well. His research had led him to the knowledge that his ancestor had been the founder of his house, and it was, again, the perfect fit. He documented all of his ideas in his journal. The diary seemed a very mundane, unworthy vessel for his soul - but it was not to be the only one, merely the first. Only Lord Voldemort had the strength it would take to weaponize part of his own soul - only he was willing to take the steps, and only he would get to the destination.
He rewarded Lucius with his old diary, just as he had rewarded Bella with the Cup of Hufflepuff, had permitted her to store part of himself in her vault. Lucius did not know what it was, but he knew what it could do: Tom Riddle had almost caused the school to close down once before, and his most mundane Horcrux, that had captured those days, could close the school again. The recent failure to disgrace Dumbledore justified resorting to more extreme measures - indeed, it proved to Lord Voldemort that he would have to get rid of Dumbledore himself, if not in body (he stroked the diary and smiled to himself) then in spirit. If it meant another mudblood would have to die - it was not his fault. His more "proportionate" measures had been futile. Yes, Lucius had proven himself more worthy - and he would be able to use it wisely to bring about Dumbledore's ruin.
"Kreacher, if someone is polyjuiced into a house elf's master and orders the elf to do something, does the elf have to-" Severus interrogated Kreacher.
"The house elves know," Kreacher informed him. House elf magic was powerful, powerful because it was extremely limited. Regulus had always realized this, and he had been feeling more and more as though his fate was to be the only one to see what everybody missed.
All they would have to do was get Lucius or Narcissa to order their elf to hand the diary over to Severus or Regulus.
It quickly became clear that they would have to stop at nothing to get what they needed.
"What about the Imperius curse?"
"Kreacher doesn't know."
The first unthinkable thing they would have to try, to destroy their master who had done unthinkable things, would be to practice the Imperius curse on one another. The absurdity of their position became increasingly evident, every day.
Regulus agreed to be Imperiused into ordering Kreacher to serve him tea with salt instead of sugar - as benign a use of the curse as they could think of, so benign that even Lily had no choice but to accept it. But the house elf's magic had prevented him from acting out a wish made under the curse, on top of causing Kreacher such distress that he had to be ordered not to shut the oven door on himself. "Why do we have to use their elf?" Regulus complained, and Severus reminded him that it was his idea.
"Can't we Imperius Lucius?"
Severus objected - this would be a death sentence either to Lucius or to them, if not for all of them. But there were other ways to get a wizard to do your bidding - finally, they managed to get Kreacher to serve Regulus a cup of salty tea, and when Regulus had no idea why Kreacher had done such a thing, Severus knew he had succeeded - Confundus was the way to go. They would take a leaf out of the Dark Lord's book and hypnotize Dobby's master or mistress into ordering Dobby to hand the Horcrux over to them, without remembering it. It was not foolproof, but it was their best option.
They had decided that using Narcissa, who had not been Marked, would be less dangerous than using Lucius, and the only one who had any business being alone with her was Regulus. Regulus practiced the confundus charm, and he quickly found out it was not his specialty. "It will take less time for me to Polyjuice into you," Severus snapped at him, eventually. They knew that even if this plan worked perfectly, they would have to find the other Horcruxes, and they still had no idea how they would destroy them, so Regulus could not understand what was so urgent about this particular problem.
"You've accomplished legilimency in thirty minutes! I don't understand why this is so hard!" Severus said, wringing his hands.
Regulus had never been in danger, he had never lived like this - only Severus was this well-versed in the mental mathematics of living in fear, and persisting through pain. The less time we spend lying to the Dark Lord's face, the better - why can he not see that? Severus still did not know why only he could remember being Marked, or how he was able to conceal things from the legilimens.
"Hey, I'm not stupid," Regulus scowled. "I'm the one who figured out what the locket was!"
Severus stared at him silently. Your being clever won't help you when he uses Crucio on you, or tells your cousin to do it to you , he thought. What use is cleverness against someone with no conscience? And I asked him to join me, I put him in peril. Regulus could have had the perfect life, and now he was in so much danger, and nothing had prepared him for this, nothing.
Severus was almost happy, picturing Regulus with someone else, safe, content, and not afraid of anything, and he hated himself for thinking it.
"I'm sorry," he whispered. "You just - we have to get this right."
For reasons unfathomable to Severus, Regulus could not master the charm.
"We should make some polyjuice just in case," he suggested. "Could be useful - who knows."
"Right, make Polyjuice, excellent idea," Severus snorted. "With what?"
Even as he mocked Regulus he thought to himself, how happy Regulus could have been if he had never walked through that door and seen Severus crying, if he'd just left him alone in the hospital wing - he never would have noticed him, or he would have forgotten about him, and each of them would have taken their natural place and Regulus would have been safe…
"What do you mean, with what? You know how to make it, don't you?"
"In my sleep, but even I would need the ingredients, Reg!"
"I asked you to stop talking to me like I'm stupid, Severus," Regulus warned him, and his patience was waning.
"If you can explain to me where we're meant to get the ingredients without stealing them -"
"At the shop, you idiot."
Ah, the world being at your neck and call, courtesy of having money.
"I can't afford it and your vault is monitored."
"First of all, I'm of age now and whatever's in there is mine. Second, my parents can't monitor the Potter vault."
"The Potter vault? What are you -"
Comprehension dawned on Severus's face mid-sentence: Lily had inherited everything. It was time to plan a trip to Gringotts.
All the while, Regulus felt his own tension levels rising, too - how on earth had he found himself on a quest to defeat the man who had been his childhood idol, with Severus and his mudblood friend, who was back in his life all of a sudden? He wanted two things, only two things - to be with Severus and to transcend his heritage - and both seemed to elude him. Worse still, things he had always taken for granted seemed to be slipping through his fingers at an alarming rate. His parents' unconditional approval, Kreacher, the knowledge that he was good, and right, the certainty that he would live… and yet, Severus had expected him to learn Confundus in an afternoon. You're not as good as him, a voice nagged at Regulus. He can make spells in hours, you can't even learn them. You will only ever amount to anything because of your name, if you ever do.
"I will never get the hang of this spell," Regulus complained, and part of him knew that he just didn't want to get the hang of it, didn't want to confund his own cousin, nor Lucius, into doing anything, certainly not something that would surely make them punish Dobby horribly, if they ever found out about it. If they could only use Imperio, it would have been so simple…
Severus accepted that he would have to do it himself - he would have to imperil Lucius, who had helped him so much, by his own hand, and he would have to borrow Regulus's likeness to do it. It's just as well , he told himself. If I could do it all instead of him, while he was safe, I would have. Regulus's likeness was not yet scarred like his. But this impediment would slow them down by an entire month, and neither Severus nor Regulus could see even a day ahead.