Hanji wouldn't be waking up anytime soon.
After carrying her to the small bedroom beside the laboratory and pulling a blanket up over her shoulders, Lock stood for a long moment at her bedside. The faint sound of the steam engine humming through the wall filled the silence like a lullaby.
He turned away and walked back into the lab, stopping in front of the still-churning machine. Its steady rhythm echoed in the room—soft, mechanical, alive.
Lock couldn't help the small smile forming at the corner of his lips.
The revolution has begun.
From this moment onward, Paradis Island would no longer belong to the past. Power would shift—not just political or military, but something deeper. The shape of civilization itself was about to change.
"The Steam Age…" Lock whispered. "Next comes electricity. But... how?"
He sighed and rubbed his temple. He was many things—a strategist, a soldier, a leader—but certainly not a scientist.
Electricity was a mystery to him, a concept that existed in vague flashes of memory from another life. He could only hope Hanji and her team could unlock that secret for real.
If only I could bring in scientists from the outside world…
But that was impossible. Those people were national treasures in Marley and the other nations across the sea. Getting even one of them to Paradis was as likely as catching lightning in his bare hands.
So for now, he had to trust his own people.
In the days that followed, Lock remained in Hanji's lab almost constantly. He handled essential military matters through messengers, but most of his attention stayed fixed on the development of the steam engine. He offered ideas when asked—mostly based on scraps of practical logic and faint memories from the world before. To Hanji and the engineers, though, even those bits of insight felt like prophecy.
Each test brought the machine closer to perfection.
Each spark of progress brought them closer to a future where Titans weren't the only source of power.
To Hanji, Lock's brilliance was both exhilarating and infuriating.
"Strong, intelligent, decisive… and now he's helping me fix engines," she had muttered once. "He's not even human at this point."
Moblit had just nodded in tired agreement. No one in the Corps tried comparing themselves to Lock anymore. It was pointless.
Lock, however, barely noticed the admiration. For him, it wasn't about pride—it was necessity.
Every discovery was a weapon.
Every breakthrough was survival.
He didn't have the luxury of being humble or proud. He had a nation to rebuild.
The steam project advanced at a breakneck pace. Within weeks, the engines were smaller, more efficient, more stable. A handful of prototypes were already being tested to power mills, pumps, and vehicles. Hanji called it "a miracle." Lock simply called it "a beginning."
But before the first machine could even be deployed, the miracle was interrupted.
The door to the laboratory burst open.
A messenger, face pale and uniform, torn from running, stumbled inside.
"Commander Lock! Urgent report from Shiganshina District! Vice Captain Levi's battalion has engaged enemy Titans. They're requesting immediate reinforcements!"
The air in the lab froze.
Lock straightened instantly, his expression shifting from calm curiosity to razor-edged focus.
"So… it's finally begun."
Hanji stirred from her desk, suddenly alert. "You're going to lead the response yourself?"
Lock nodded once. "I have to. There's no one else available to command at that level."
Hanji frowned. "That's not true—you have officers—"
"They're not ready." Lock's tone was quiet but final. "We've just reorganized the Corps. Most of our experienced leaders are either integrated into Erwin's command structure or handling internal stability operations. If I send anyone else, it's a gamble. And I don't have time to gamble."
His words carried the weight of logic, but beneath them, Hanji heard something else—guilt. Responsibility.
He had built this world. If it was to be defended, it had to be by his hand.
Hanji hesitated. "Then at least promise me this: you'll come back."
Lock smiled faintly. "Don't worry. I haven't seen our new era yet. I still have to watch you turn steam into lightning."
Hanji scowled. "Don't make jokes about dying. Not when you're about to ride into hell."
"I'm not joking," he said gently, then turned to leave. "I'll be back before you finish the next engine."
Command Headquarters — Wall Sina
By the time Lock reached the central command building, his personal guard was already assembled. Petra, Ymir, Erwin, and even Darius Zackly were waiting in the office, grim-faced.
Erwin spoke first. "Let me lead the expedition this time."
Lock shook his head. "You can't. The reorganization of the Military Police and Garrison Corps is at a critical stage. If you leave now, everything we've built here collapses."
Erwin's expression hardened. "You're too important to risk. You know that as well as I do."
"Exactly why I have to go," Lock countered. "Zeke Yeager is on the field. If what Levi's scouts reported is accurate, Marley's finally made its move—and the Beast Titan is leading them. That means my presence isn't just reinforcement—it's strategy."
Zackly leaned forward, his voice heavy. "You're the only person who understands the entire network of our current operations, Lock. If you fall, there's no replacement. Paradis will be headless."
Lock's lips tightened. "If I don't go, Paradis may not have a future at all."
Silence.
It wasn't arrogance in his tone. It was true.
Every major reform, every law, every military doctrine—they all stemmed from him. The others executed, but he planned. If Paradis was a body, Erwin and Zackly were its heart and hands.
Lock was its mind.
Both men exchanged a glance. For once, even Erwin had no rebuttal.
Petra finally broke the tension. Her voice trembled slightly. "Then at least take me with you."
Lock turned to her. "No."
"But—!"
"The Survey Corps can't function without you right now," he said gently, though his tone left no room for argument. "You're coordinating internal defense, logistics, and training. If something happens here while we're gone, we lose more than a battle—we lose control of the Walls."
Petra bit her lip. She hated that he was right.
Still, the thought of him leaving—again—twisted painfully in her chest.
She looked away, muttering, "Then take Ymir with you. She's strong enough to make a difference. If she's there, at least you'll have a chance."
Lock's eyes softened slightly. "...All right. I'll ask her."
Before Petra could respond, a familiar, drawling voice came from the doorway.
"No need to ask," said Ymir, stepping inside with her usual half-smile. "I already heard. If you're going to fight Marley, you'll need me."
Lock raised a brow. "You're volunteering."
"Let's just say I owe you," Ymir replied. "Besides, Christa would kill me if I stayed behind while the rest of you risked your lives."
Despite himself, Lock chuckled. "Fair enough."
He turned back to the others. "That settles it. I'll take Ymir and a strike unit of the Survey Corps. We'll move fast and reinforce Levi before sunrise."
Zackly nodded reluctantly. "Then may the Walls protect you."
Erwin clasped Lock's arm in the old soldier's grip. "Be careful out there. You're carrying more than orders—you're carrying the island's future."
Lock smiled thinly. "Then I suppose I have every reason not to die."
He turned to Petra, who was still watching him, eyes glistening but defiant.
"Take care of things here," he said softly. "When I return, we'll begin the next phase."
She swallowed hard, forcing a smile. "You'd better keep your word."
Lock paused at the doorway, looking back one last time.
"I always do."
Then he was gone—his coat flaring behind him, footsteps echoing down the corridor.
Outside, the sky was beginning to turn red with dusk.
The wind carried a faint chill from the south—the scent of rain, and smoke, and something else.
War.
Lock inhaled deeply, then looked toward the horizon beyond Wall Rose.
"Hold on, Levi," he murmured. "I'm coming."
And with that, he mounted his horse and rode out, Ymir and a dozen of Paradis's finest at his back, heading straight for Shiganshina—where the Beast Titan waited.
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