Author's Note: Some short applications of magical contracts, as mentioned in Goblet of Fire and demonstrated in Order of the Phoenix and Half-Blood Prince.
Yes, of course they can't possibly work this easily in canon, because the plot would implode six ways to Sunday through no fault of its own - the implications of readily-available magically-binding contracts would cause fundamental changes in the worldbuilding, the entire plot would be impossible because wizards hundreds of years ago would have written all the problems out of existence (or enshrined them as fundamental laws of reality), some poorly-phrased contract would have accidentally wiped out a third of the world's population, etc. This is just having a bit of fun.
Hermione Gets Promoted
"It's very simple," Hermione said sweetly to the gathered students. "As you can clearly see, all the contract states is that you vow not to enter the service of He-Who-Must-Not-Be-Named. I'm sure that we can all agree that no one here would ever aid such a vile wizard, so it shouldn't be any problem. The Minister himself approves. All you need to do is sign here..."
Harry shuddered; he was uncannily reminded of Umbridge. What had he done? All he had meant to do was get Scrimgeour off his back and take advantage of the skill Hermione had shown last year with the sign-up sheet for Dumbledore's Army. He hadn't expected for her to take such a shine to the job...
Riddle Did His Homework
Voldemort sighed as a perfectly good servant - up to that point - abruptly gurgled and dissolved into a thrashing mass of amorphous flesh. The other Death Eaters backed away; the less experienced ones actually shrieked, while the older ones, who had seen traitors before, merely averted their eyes.
What had set Severus off? Well, there was no telling now. Just as there had been no telling with Regulus. Young people these days...
The Dark Mark wasn't just a pretty tattoo. By taking it, the receiver agreed to serve Lord Voldemort through all eternity, until death did them part. (Their death, of course, for he would never die.) Betrayal brought swift and brutal retaliation from the broken contract. Quick, easy, and legal: he was puzzled why more did not follow his example. Of course, the more flashy sort of retaliation required a modicum of research, but the fundamental principles were simple. Crude but effective punishments were easily within the reach of a talented fifth-year.
Perhaps Hogwarts's standards had just fallen down since his day?
A Well-Ordered Phoenix
"Dumbledore, please! You have to help us!" A white-faced James Potter burst into the meeting room, dragging a petrified body along with him. "It's - it's Peter! Something happened to him! We've tried every counterspell we can, but-" He broke off and squeezed his friend's hand, for all that he might have been gripping a stone. "You have to help him!"
Albus took one look at him, then sighed deeply. "I am afraid young Mr. Pettigrew has brought this on himself."
"What?" James shook his head furiously. "No! He didn't deserve this! We all get up to crazy things, but-"
"He planned to betray us all."
James froze mid-sentence, for a moment as inanimate as his friend. Then, he shook his head again, wild hair flying everywhere. "Peter would never do that! None of my friends would!"
"Do you remember the contract you signed when you joined the Order, James?" Albus said, sagging into his upholstered armchair. He felt very old. "The one that required a drop of your blood?"
"Yes, but what's that got to do with it?" Incredulity aside, James was no fool; a moment later, shock, then indignation, flashed across his face. "You did this to him?"
"The contract was a simple and ancient one," Albus said in a tired voice. Yes, so ancient... "All it required was that the participating parties were forbidden to act against each other by word or deed."
James pulled a face. "That... isn't that a marriage contract?"
Albus grimaced. He remembered well enough without the reminder. "A modified one," he elaborated. "Not quite a marriage. Just... a bond of allyship and friendship. You did read it, did you not?"
"I agreed with all the language," James said vaguely, in a nervous sort of voice that implied he hadn't realized just how binding it was. "But... can you be certain that's what happened to Peter? Couldn't it be that he accidentally triggered a clause, or a loophole-"
"I can assure you, the wording used in that contract is capable of functioning for decades without a false positive. Or a false negative." No, he'd had to employ - No, there was no use reminiscing. It only bored young men, and with good reason. As an arrogant young man, he'd always privately sneered at sad old men as miserable and self-absorbed wastes of air. As a sad old man... he was the exemplary example. "You are correct, however, that I do not know it was retaliation from this contract." He spent seven seconds swishing his wand through the necessary motions. "I did not know. I know now."
"Peter would never betray us," James repeated, but there was less conviction now. "Maybe - maybe he was Confunded, or put under the Imperius, or something like that. That could trigger a false positive, couldn't it?"
"I am afraid that the contract's terms would only be triggered by willing action."
James did not believe him. Not fully. That did not matter. "So - what? Peter's going to be like this forever?"
"Mr. Potter, I am not that sort of wizard," Albus said with a touch of asperity. "No. As the holder of the contract, I may revoke his punishment, and he will regain full mobility on the spot. It will be as though he were never harmed." Now he eyed Pettigrew. How well did those glassy eyes still perceive their surroundings? "However, the moment that he moves against us once more, motion will be denied to him once more. And so on, and so forth. I have no interest in releasing anyone from the contract itself for the duration of this war, and especially not one who has already shown a proclivity for violating it. Am I understood?" The question was directed as much to Pettigrew as to James.
"Whatever he did, I'm sure he won't do it again," James said with conviction. "Look, he's always been a bit - easily influenced. Maybe we've been neglecting him, the rest of us. We'll get him back on the straight and narrow again, and he'll be the best, most loyal friend anyone could ask for. I'm sure of it. He's got to have learned his lesson, anyway - scared him straight." He gave Albus an ingratiating smile. "So, sir - will you please, please release him?"
They went back and forth for a little while longer, but Albus was too old and too cynical to think he could reason with an idealistic young man. James would believe no ill of a friend. That was simply how it would have to be. Stupid young men thought they were young and invincible and their bonds of fealty outshone all that had ever existed; Gilgamesh and Enkidu would have quailed before the undying strength of schoolboy friendships - in the opinion of schoolboys. Well, let them think so. The glories of youth arrived far too quietly and departed far too quickly...
Thus he freed Pettigrew from his immobility, and the young man promptly collapsed into tears and wailed proclamations of gratitude. Such contrition no penitent had ever felt; such slavish declarations of renewed loyalty no emperor had ever heard. Oh, the pathos, oh, the ecstasy...
Albus only sat there and wondered to himself how long it would be before the next violation of the contract. Twenty-four hours? Three or four days? Less?
But Albus, sad and jaded old man that he was, turned out to be far too unkind to young Mr. Pettigrew. He made it a full two weeks.
A Less-Dippy Dippet
"...and so the terms of this contract are really quite simple. You vow that you will not engage in any behaviors construed to be part of the 'Heir of Slytherin's' activities, including leaving threatening messages around the school, engaging in interactions with 'Slytherin's Monster' that would endanger other students, or assaulting Muggleborns with intent to maim or kill. I am sorry that it has come to this, but we have been quite fortunate so far with the absence of deaths. Should the pattern of escalation continue, I fear we may suffer fatalities." The Headmaster unfurled the parchment. "I would like everyone to come forward, with position in the queue determined by year and House, and sign their names for all Hogwarts to witness.
"You may, of course, choose to abstain... which will be treated as a formal withdrawal from the school. In addition, future employers will be notified as to why you chose to withdraw from Hogwarts... So please, do choose wisely.
"No objections? Very good. Then let us begin..."
No Good Deed Goes Unpunished
Bartemius Crouch was not a drinking man.
That was fortunate, as he would have been at the bottom of a bottle if he were. This had been a wretched week.
It had been such a simple and innocuous idea. All he'd asked the Aurors to do was sign oaths of fealty to the Ministry. Small print specified that there were to regard the Ministry's enemies as their own - surely an obvious part of such an oath - and never give such vile criminals aid. Simple. It was simple. Half the wonder was that they weren't forced to do it in the first place.
Obviously, that had been because the staffing quotas would never be filled otherwise. Half the Aurors were in St. Mungo's, another sixth were struck with the sickness that indicated they had indirectly - through negligence or willful blindness - aided the Ministry's enemies, and the remainder were in an uproar over one thing or another. If it wasn't indignation at the cruel punishment into which he had tricked their comrades, it was indignation at the poor screening that had forced them to accept such backstabbing scum as comrades. If only he could stockpile Howlers, he could have used the self-igniting letters to warm his house all through the winter.
In a show of goodwill and proof that he had treated them all fairly, he hauled his son in to grandly sign the oath himself for all of them to witness. It was about time the boy did something for him for once - he ought to be delighted, after all. For so long, he had whined to his mother that Barty never paid attention to him, and now he had the chance to be the center of attention! He could make his father proud! All he had to do was sign the damned contract...
Unfortunately, he'd summoned up enough intelligence - from some immense depth within his being, Merlin knew Barty had never seen any sign of it before that point - to read the fine print, and promptly bolted. Even more unfortunately, when he'd been tackled and wrestled to the ground, his sleeve had flown up, and...
Barty sighed and massaged his temples. The throbbing pain in his head would not go away. The mediwitch, before things had gotten so bad, had claimed it was due to stress and advised him to cut back on work for the sake of his health. He could only imagine what she would tell him now.
Sitting and stewing in his own rage and sense of injustice was unproductive, of course, but such self-indulgence in wanton self-pity was all that was keeping him from getting out of his chair, very calmly walking down to the holding cells, and throttling that rotten whelp of a son with his own hands. Son? No, he had no son. That rotten whelp of a Death Eater.
Dear Merlin, maybe he should take up drinking. The grand edifice of his life, for which he had worked so hard and done so much thanklessly and joylessly, was already a great smoldering ruin. How much could throwing alcohol on the flames make things worse?
Day of the Toad
"By Ministry Decree 2401, I hitherto require all students to sign this binding magical contract requiring that they not speak out against our glorious Ministry and the proper and approved version of events." A fly buzzed past that hideous, smiling mouth. Harry half-expected a tongue to whip out and snatch it. "Refusal will be treated as a crime and be punished accordingly." The girlish little giggle accompanying the words drove home the knife - as he was sure she intended.
"Can she even do this?" he asked Hermione, who was clutching the edge of the table in a white-knuckled grip.
"There's nothing magically preventing her from doing this," Hermione said, staring at Umbridge as though she had just beheld the Devil Herself. Given the talk of binding magical contracts, perhaps it was apt. "There are legal restrictions, but if she's somehow bypassed them-"
"We won't do it!" Ron whispered furiously. "They can't imprison all of us!"
But, deep in his gut, Harry knew they could. Azkaban was empty, and the Dementors hungered...
The Guilty Flee
"...you might need to trust him utterly and without reservation, James, but I don't." Lily turned back to Sirius and Peter and flourished the contract. "All I ask is for the Secret-Keeper to sign his name to a contract promising not to betray us. Is that so much to ask?"
"W-what happens if - I mean, technically, somehow, maybe the magic goes wrong - the contract d-decides it's broken?" Peter stammered out.
Lily smiled beatifically. "You could always sign and find out."
Five seconds later, as Peter jumped out the window to get away, Lily turned to James and raised an eyebrow. "Now, I want an apology over that brilliant scheme of making Peter the Secret-Keeper."
"Is that even a real contract?" he grumbled, wiping off his glasses and peering at it closely. Lily's beatific smile widened.
"That's the beauty of it, don't you see? I never did say it was a magical contract."
Wizarding Divorce Court
"...and so you see, your Honor, Mr. Dumbledore clearly intends to dissolve this contract in order to violate it. As such, he should be subject to the full extent of its punishments under magical law..."
"Mr. Grindelwald is incorrect. I merely disapprove of his actions and wish to dissolve this contract as a sign of my disapproval. If we come into conflict thereafter, that will be due to my choices and his. Surely it is within the rights of free wizards, which we both will be, to disagree?"
"Objection! As you will see from these Pensieve memories, Mr. Dumbledore clearly conspired with an intermittently-employed lowlife to set a Niffler upon me and steal the binding item of the contract. Such thievery of a precious sentimental item is clearly malicious action, which -"
"I assure you, the Niffler's actions were merely a happy accident. Young Newt has scarcely any control over-"
"Oh, is he Newt to you? Have you moved on, Albus? I'm so happy for you that you've found someone new! Oh yes! Tell me, what is it that appeals to you about him - the curly hair that reminds you of me? Or the vacant stare that reminds you of Ariana?"
"I refuse to dignity this vulgarity with a response. And you're one to talk, considering Credence."
"Ah, so you do dignify me with a response!"
"That was not a formal response-"
"ORDER! Order in the court! Behave like grown wizards, both of you!"
"Oh, who do you think you are - Merlin Himself? So what if you are? I bear the Elder Wand!"
Merlin Ambrosius, Grand Arbiter of Magical Contracts in Perpetuity, buried his face in his hands and sincerely considered expelling both these idiots from the plane of Magical Law into the world of mundane reality once more. On the other hand, the next case in line was the Fates' seventh demand for long-range time-travel - never mind that it made a horrid mess of the skein, they had grown lazy in their old age - on behalf of some idiot who had gotten himself killed before fulfilling his prophesied destiny and popping out a dozen sickeningly perfect babies with his soulmate. For the moment, at least, these two were easier to tolerate... for the moment...
Avoiding The Contract
"Wait - it says right here at the very bottom that, if I claim the Slytherin Lordship, I agree to pay all their unpaid debt, including the never-paid fees for construction of the Chamber of Secrets, with 'appropriate interest'. What's that mean? How much is appropriate? And exactly how much debt do you accrue over a thousand years of compounding interest?"
Ragnok sighed. Damn these Muggle-raised Half-Bloods. He'd never met an eligible Pureblood that didn't snap up the "unclaimed Lordship" gambit the moment it was offered...
The Wages of Sin Are Death
"I can only imagine how trying this entire legal process has been for you, especially after He-Who-Must-Not-Be-Named forced you to commit such terrible acts in his service." A paper was slid across the table. "Against the horrible case he should ever return, this contract will expedite your future freedom for any such charges. It's very clear: if you willingly serve him ever again - what am I saying, of course you never served him willingly in the first place, hmm? At any rate, if you should ever come to serve him willingly, you will die on the spot. And you have sworn you would rather have died than have been forced to commit those awful deeds in his service, have you not? So consider this a mere formality as the final step in clearing you of all charges. Otherwise... if his grip is still too strong upon you, I'm afraid that - strictly as a safety measure, you understand - we will have to hold you in Azkaban until his influence fully fades..."
Death Eater after Death Eater stared into the burning eyes of Bartemius Crouch and, hands shaking, picked up the offered quill and signed their names. The choice between the Dementors now and the Dark Lord's wrath at some potential future time - who would make any other choice?
Well, except for Bellatrix Lestrange, who picked up the quill and promptly attempted to put Crouch's eye out with it. But she had always been a little touched in the head.
Thirteen years later, the Death Eaters felt their Dark Mark burn. Most sat tight and trembled; some, buckling under the pain, cut off their left forearms and had their wives push them through the Floo to St. Mungo's. Only a few responded to the call.
Harry Potter furrowed his brow as half a dozen cloaked men appeared in the graveyard and promptly dropped dead. "I didn't realize 'Death Eater' was such a literal name," he said to Voldemort, who looked appalled.
It would turn out that the entirety of Voldemort's support base in Britain was Peter Pettigrew (who had never seen the inside of a Ministry holding cell), Bellatrix Lestrange (who had refused Crouch's black bargain), and Barty Crouch Jr. (whose enraged father had refused to offer him the plea deal). Furious and desperate, Voldemort would attempt to make a go of being a one-man army, only to give up in disgust after a year and seek a new life abroad. Undergoing reconstructive surgery and taking up his old name of Tom Riddle, he soon "found religion" and took up a prosperous life on the preaching circuit, gathering masses of followers, money, and notoriety with none of the bloodshed and hardship. By far his greatest draw was his miraculous snake-handling act, which earned him runaway popularity with fringe Pentecostal sects and Las Vegas audiences alike.
Harry Potter went on to live a happy and prosperous life, marred only by a brief period of growing emotional instability, brain fog, and crippling headaches. Upon his friend Hermione's advice, he visited Muggle brain specialists and eventually had a massive tumor removed; Harry made a full recovery thereafter, and the surgical team made a mutual pact of secrecy over the foul black ichor that had dripped from the grotesque tumor and the hateful, hissing voice they had heard as they held the oozing lump in their hands. All was well.
As for Dumbledore, he had learned a certain odd piece of trivia about the elder Crouch during the man's memorial service: part of Crouch's determination and drive to succeed came from having to work his way up from a rough start in life, for complications during pregnancy had caused him to be born two months premature - or, put another way, as the seventh month died.