By the end of autumn of his tenth year, Cassius found the tempo of his life shifting.
The Arcanum was no longer the half-formed gathering of prodigies and brilliant minds; it was a proper engine now, humming along, grinding out projects capable of changing the magical world in subtle but irreversible ways.
His corporations in the Muggle world gave him money, reach, and laboratories that no ministry could regulate.
But Hogwarts—the old castle itself—was the next crucible, the place where his plan would move from theory to reality.
The reports from his agents trickled in like rain, steady and unending.
And they all spoke of one thing: expansion.
~
For the first time in centuries, the school was bursting at the seams.
The surge of Muggle-born admissions Cassius had engineered had not faded—it had doubled.
By the time he set foot in the castle next year, Hogwarts would host nearly fifty percent more students than they had seen in the last 50 years.
The solution was inelegant but telling: more professors.
Additional staff were being contracted on short-term basis, enough to split classes into halves, sometimes thirds.
Ancient Runes, Arithmancy, even Transfiguration now had assistant professors working beneath their heads.
McGonagall, for all her competence, could not possibly handle six parallel first-year classes alone.
But the real experiment was Defense Against the Dark Arts.
That position was cursed, everyone knew it—even if the Ministry refused to put it in writing.
For decades, no professor had lasted longer than a year.
Some died, others resigned, a few were driven mad, and one or two had simply disappeared.
The curse was Voldemort's legacy, a scar left on the school itself.
The first solution Cassius had thought up: Divide the curse.
Instead of a single unlucky professor, Hogwarts would host two or three Defense teachers, each covering portions of the curriculum.
The hope was that no one person would bear the brunt of the curse entirely, that by sharing the burden they might outwit whatever shadow of Voldemort lingered on the post, encountering only troubles but not fatalities.
Cassius read that report with a thin smile.
The headmaster was desperate.
He was forced to react quickly calling in new teachers to handle the mountain of fresh students lest he be criticized for his mismanagement of the school.
That meant Cassius' pressure was working.
For it was exactly this reaction that would cause dumbledores reputation to fall, instead of if he'd just asked the teachers to buckle-down and solve the problem by using time-turners to handle the higher volume of classes without increasing the number of teachers.
~
But Hogwarts was not his only concern.
The old names, the remnants of the Order of the Phoenix, were threads left dangling.
Sirius Black.
Remus Lupin.
Peter Pettigrew.
All three had their roles to play.
Sirius was still rotting in Azkaban, blamed for crimes that were never his.
Clearing his name too soon would draw unwanted attention—Cassius knew he would need the Weasley boy, Ron, and his rat before he could prove the truth.
But breaking Sirius out?
That was… tempting.
A man like that would be a weapon, loyal to those who freed him, mad with rage but sharp with instinct, even having the Black family's excessive library and resources to his name, Cassius being his unofficial godchild could even grant him the right to become the black families heir in place of being the Potter heir.
The problem was timing.
Cassius had no intention of showing his hand before he ever set foot in Hogwarts.
No, Sirius could wait.
A few more months in Azkaban was nothing compared to the storm he would unleash once free, just so long as he acted before the summer after his 2nd year when the weasleys would be featured in the prophet for winning the wizarding lotteries prize a small fortune.
Remus, however, was a different matter.
The werewolf was useful.
A man of intelligence and principle, wasted by a curse that shackled him to the moon, not even a curse of his own choosing but of revenge against his family.
Dumbledore tolerated him out of pity; most of wizarding Britain dismissed him as a danger or a pariah.
Cassius meanwhile saw a tool, one just as useful to him as Sirius Black.
The Wolfsbane potion, recently invented, gave Remus back his mind during transformation—but left him powerless, a wolf in a cage, while the potion itself was expensive to aquire and with the stigma in the community against werewolves the job options were... well not that great.
So Cassius intervened having located the wandering wizard years ago thanks to job postings in the Daily Prophet and enlisted his help as an 'experimental' subject within the Arcanum.
The topic was about finding a cure for the condition, a cause Lupin was more than willing to throw his life away for.
Though getting rid of the curse seemed wasteful to Cassius so instead of finding a cure to turn him back purely human instead he used his memories of another world, another fiction, where lycanthropy was not a chain but a weapon.
There, men turned wolf at will, retaining their strength and instincts without losing themselves.
Lycans, not beasts.
He shared this theory with the Arcanum.
They dissected it, expanded it, tore it apart and rebuilt it.
What began as a half-remembered dream from his old life became a working project: a transformative brew, not a cure, but a rewriting.
After trialing it one beasts infected with lycanthrophy the results were impressive showing that some could maintain their origional states while others transformed when enraged.
Having seen the raw data of years of testing Lupin was keen to volunteer himself for the treatment.
It wasnt a cure, but after seeing how hard the team worked, only to result in a solution rather than a cure his mindset changed, agreeing that while a cure might be possible would it be worth waiting another decade to finally get one, rather than adopt the solution already discovered.
For the first time in years, the man had hope.
Before being allowed to proceed Lupin was presented with a magical contract, one the man read over and over seeking ever clause for loophole or things detrimental to himself.
In the end he spotted nothing, though he would be bound to the Arcanum and Arcana for the rest of his life he would otherwise be free and this was a deal he could easily accept in exchange for what he was receiving.
After taking the potion Lupin would be effectively cutting his ties with Dumbledore and his old life, having joined Cassius and fighting on his side instead.
When comparing the old man who manipulated and used him without ever trusting him, and the mysterious shadow lord who gave him wealth, worth, and happiness there wasnt even a moment to think twice before deciding.
One by one Cassius began dismantling the order, both former and future members adding them into his own pocket.
~
And then there was Pettigrew.
The rat still lived, hiding in plain sight as the Weasley family's pet.
Disgusting.
Treacherous.
Weak.
But useful.
Cassius knew the truth that no one else did—that Peter had been the Potters' betrayer, that he had framed Sirius, that he was Voldemort's pathetic servant still waiting for the call so that he could flee the dangerous wizarding world to reside safetly by his strong masters side.
He could not yet move against him.
To strike too soon would unravel the delicate timeline.
He planned to wait till the end of his first year at school, snagging the rat on the trainride home from Ron, while depriving Harry the chance of revenge entirely, as that honor is more deserved to Sirius.
~
As for the other members, Mad-Eye moody was a staunch supporter of Dumbledore and even after being approached by the Arcanum he refused to join, citing he was enjoying his retirement.
But the young graduate of Hogwarts Nymphadora Tonks was easily recruited joining the organization rather than becoming an Auror with the ministry.
Amelia Bones was being actively solicited and before to long she would likely join the Arcanum rather than follow in he brother Edgars footsteps joining Dumbledore.
Mundungus was a lost cause why would Cassius want anything to do with the man, he was a coward and hardly an asset even if he tried.
The largest pieces were Frank and Alice Longbottom, Cassius committed great amounts of galleons and brainpower on fixing the couples condition, performing a miricle that even the best at St. Mungo's couldnt manage to do.
Allowing the couple to rise from their near catatonic state after almost a decade, returning to the lives they left behind, and preparing their young son for the coming hogwarts term.
Snape... well he would be recruited in time but not until after Cassius had, had his grand reveal first.
Future members to be solicited would be Kingsley Shacklebolt, easily recruited when the New Dawn takes power in the muggle world.