In LOTR with Harry Potter system

Sylas watched the great dragon, still alive and thrashing within the sphere of water suspended above the lake.

Frowning with determination, he raised his wand and cast his most advanced Transfiguration charm. The swirling water shifted shape, slowly morphing into a colossal serpent, larger than Smaug himself, which then coiled tightly around the dragon's massive frame. As the last coils locked into place, the serpent's form shimmered and hardened, transforming into enchanted iron chains that bound the dragon from snout to tail.

The moment the spell completed, Sylas staggered back, gasping for breath. His face had gone pale.

Transforming something so massive pushed him to the brink. If not for the energy flowing from Gandalf's Ring of Fire, he doubted he could have pulled it off.

"Are you alright?" Gandalf asked from above, his voice carrying gentle concern as he stood poised atop the dragon's back.

"I'll manage," Sylas replied, shaking off the exhaustion. "But we have to finish this. While we still can."

Smaug, for the moment, lay helpless, his wings pinned, limbs shackled, and maw tightly sealed. It was the first time he had been truly vulnerable in centuries.

Wasting no time, Gandalf gripped the hilt of Glamdring, still embedded in the dragon's back, and yanked with all his strength. The blade came free with a slick sound, followed by a plume of searing, molten blood.

Meanwhile, Sylas moved to the creature's wounded wing, where the spear Aeglos still protruded. Bracing himself, he grabbed the silver shaft with both hands and pulled, muscles trembling. As it came free, more lava-like blood spilled from the torn flesh, and the beast let out a low, agonized groan that echoed across the lake.

With a flick of his wand, Sylas levitated the enormous dragon's body and gently rotated it, so its broad chest now faced the sky.

Together, the two stared down at the infamous weak spot, the one place not covered by impenetrable scales. But instead of a bare patch, they found it sealed with a glossy, black mass: the remains of Bard's molten black arrow, now hardened into a near-invulnerable plate.

Smaug had no weak spot now. Not one an ordinary warrior could reach.

But Sylas wasn't ordinary.

With slow precision, he tapped the center of the blackened mass with his wand. The dark metal shimmered, then warped under his spellwork, reshaping itself into a thick, glowing spike, an iron nail that pierced downward, sinking into the dragon's heart.

Smaug thrashed wildly, his body convulsing as pain and fear overtook him. His eyes, wide with terror, met Sylas's.

'No! Don't kill me!' his voice echoed telepathically, his real mouth unable to form words behind its magical bindings. 'I surrender! I swear it! Spare me, wizard! I'll leave, I'll never return. My treasure hoard, take it all! Just let me live!

The mighty dragon, once the terror of Erebor, now pleaded for his life with a desperation no one had ever imagined possible.

Gandalf narrowed his eyes the moment he saw Sylas pause.

For a brief second, he feared the worst.

"Don't be fooled, Sylas," the wizard warned, stepping forward on the scorched lakeshore. "Dragons are master deceivers. Their tongues are sharper than their fangs, and their words are laced with enchantments. Their lies are as potent as their fire."

But Sylas only smiled and shook his head, calm and unshaken.

"Don't worry, Gandalf," he said. "I'm not the kind of fool who makes deals with dragons out of sympathy."

He turned back toward the bound beast, still thrashing faintly beneath the weight of the enchanted chains.

"I just thought of something better than killing him."

Gandalf blinked. "Better than killing him?"

Sylas nodded. "I want to bind him. Not in chains, but in oath."

"I have a magic contract, it requires three parties: two signatories and one neutral witness. Once formed, it creates an absolute magical bond. Neither side can break it. If one violates the terms, the magic enforces the penalty."

He held up the scroll, its ancient runes pulsing faintly with golden light.

"I want you to act as witness, Gandalf. Smaug will serve as the second party. If he agrees to serve under me, truly and completely, the contract will do the rest."

Gandalf hesitated, frowning deeply.

"Binding a creature like Smaug is no small thing," he said. "His malice runs deep. If he breaks free…"

"He won't," Sylas said, with a confidence that almost startled the old wizard. "He can't. That's the nature of the contract."

There was a quiet moment between them, filled only by the distant crackle of dying flames on the lake.

"Very well," Gandalf finally said. "If anyone can tame this firestorm, it's you."

Sylas nodded in thanks, then turned back to Smaug.

The dragon lay still, watching warily. His massive golden eye focused on Sylas, noting the wand in one hand and the radiant spear Aeglos in the other.

"Smaug," Sylas said coldly, his voice amplified by magic. "You've heard everything. Answer me now. Will you swear an oath to serve me?"

He pressed the tip of Aeglos lightly to the dragon's brow. It hissed against the scales, sending a sharp sting down into the dragon's nerves.

"If not, I'll end it here. No more chances."

Faced with death, Smaug's eyes flickered. His pride battled his survival instinct, then, with a snarl masked as submission, he gave a slow nod.

"I… accept," he said, a glimmer of cunning flickering in his expression. "I will serve."

Sylas sneered inwardly.

He didn't care if the dragon was sincere or not. Once the contract took effect, Smaug's will would mean nothing. The magic would bind his very soul.

Moving swiftly, Sylas cast a Muffliato charm over himself and Gandalf, and obscured them further with a light glamour so Smaug couldn't read their lips or listen in.

He handed Gandalf the contract scroll.

As Gandalf read, his eyes widened.

Lines of enchanted runes outlined clauses that ensured full subjugation, eternal loyalty, and painful consequences for betrayal. And the final clause, crafted by Sylas himself, made it impossible for Smaug to even think of harming his new master.

By the time Gandalf looked up, his expression had changed from wary doubt to astonished admiration.

"Sylas…" he said, voice low, almost in awe. "You never cease to surprise me."

Outside the veil of silence, Smaug watched the two intently. He could see their mouths moving, but no sound reached him, and the change in Gandalf's attitude made him feel a vague sense of unease.

Not long after, Sylas lifted the Muffliato charm, and the sounds of the lake and the dragon's labored breathing returned to the air.

"Smaug," Sylas said coldly, his voice hardening like steel. "From this moment on, you will obey my every command without hesitation."

He took a step forward, Aeglos gleaming faintly in his hand.

"If you waver, even for a heartbeat, I'll drive that iron spike in your chest straight through your heart."

The dragon's slit pupils trembled, and the iron nail embedded in his chest gave a twitch, just enough to make the scaled flesh around it ripple with pain.

Smaug swallowed, his massive frame shifting uneasily. But the killing intent in Sylas's gaze was unmistakable.

"I hear you," Smaug said at last, his voice low and strained. "I will obey."

Sylas didn't waste another second. Time was of the essence. He stepped forward and placed his palm firmly against the dragon's brow, a soft glow emanating from his hand. The ancient contract spell began to hum to life.

Gandalf, standing beside them, drew the wand Sylas had crafted for him long ago. He placed its tip gently atop Sylas's hand, where it met Smaug's scales.

"Smaug, great dragon of the North," Sylas intoned, his voice solemn and laced with magic. "Do you willingly submit to me, binding your will to mine?"

At that moment, Smaug felt it, an invisible net of magic wrapping around both of them, thick and unyielding. This was no ordinary contract. It reached deeper, into the soul itself.

Realization dawned.

He had thought it would be like any other magical agreement, full of loopholes, tricks, clever wording he could someday exploit. Then, when Sylas least expected it, he would strike, tear him apart, and reclaim his pride.

But this? This was ancient soul-binding magic. Unfamiliar, foreign, deadly.

Panic surged.

Before he could even attempt to protest, the iron nail in his chest pulsed and grew, sinking deeper toward his heart. Smaug let out a strangled roar as a jolt of soul-piercing pain shook his entire being.

He could feel the tip grazing the core of his life.

"I agree!" he howled. 

The very instant the words left his mouth, Gandalf's wand flared.

A red-gold flame, thin as thread and sharp as a blade, snaked from the tip, curling around Sylas's arm and Smaug's massive neck. It sank into their flesh and left behind a glowing pattern, etched into them like a molten tattoo.

"Smaug," Sylas said again, his eyes fixed and voice unwavering. "Do you swear, from this moment until your death, never to betray me, never to bring me harm in thought or deed?"

"I swear it!" Smaug cried, faster this time.

Another thread of flame danced forth, weaving a second pattern across Sylas's right arm and deep into the dragon's neck.

"Do you swear to obey my commands without delay, hesitation, or rebellion, for as long as you live?"

"I swear!"

One vow after another was laid.

Thanks to Gandalf's sharp memory and legal mind, the contract covered every possible clause: no tricks, no linguistic loopholes, no magical mischief. Sylas swore nothing in return, only the dragon was bound. The spell was foolproof.

By the end, Sylas's forearm gleamed with golden-red markings that shimmered faintly under the starlight, elegant and ominous.

With the contract complete, Sylas gave a final flick of his wand, and the chains binding the dragon's limbs vanished in a ripple of light.

Smaug was free. And yet… not.

The vows now curled around his very soul like a collar. If he even thought of betrayal, the tattoo on his neck would ignite like molten iron, cutting off his breath, strangling him with the force of an invisible Cruciatus. And if he dared to attack Sylas, the bond would kill him before his claws could even twitch.

The once-mighty dragon lowered his head, his voice reduced to a hushed murmur.

"Master," Smaug said at last, humbled and defeated.