Traveling to ancient tribes to build infrastructure

Ariel snapped her eyes open. A blinding pain sliced through her skull, hot and sharp, like a white-hot wire carving into her brain. She gasped, her chest heaving against the thin fabric of her shirt.

"Where am I?"

The last thing she remembered was the screech of tires. The intersection. A delivery truck running a red light. Then—nothing. Just darkness. Just silence.

She was supposed to be dead.

Her vision swam, dark spots dancing before slowly solidifying into shapes. Towering figures surrounded her. Mutated humans. Their shoulders were broad, their arms thick with corded muscle, skin marked by rough patches of scales or coarse hair. The air stank of sweat, unwashed bodies, and something metallic, like old blood.

A bitter wind whipped across the open square, cutting right through her flimsy clothes. She shivered violently, her teeth chattering so hard she thought they might crack.

Then the memories hit her.

Not hers.

The original Ariel's.

Desperation. Fear. Hunger. The terror of being a weak rodent-variant female in a world that crushed the weak underfoot. The mandatory pairing. The auction block.

Ariel staggered mentally, trying to process the flood of information. *I've transmigrated,* she realized, her chest tightening. *Into a beast-world novel. Into a background character who dies in chapter three.*

In her previous life, she had been an engineer. Seven years of structural design, three years of on-site construction management. She had drawn blueprints for bridges, calculated building loads, argued with contractors on job sites more times than she could count. She knew how to build the sturdiest structure with the least amount of materials. She understood exactly what value a "sick man" could have—if someone knew how to use the weakest pieces to build a defense.

"Ten seconds!" a guard bellowed from the high platform, his voice booming over the murmuring crowd. "If you don't have a partner in ten seconds, you get assigned to the border patrol squads!"

Three massive figures detached themselves from the edge of the crowd. Scars crisscrossed their faces. Their eyes, greedy and predatory, locked onto Ariel. They moved toward her, their heavy boots thudding on the packed dirt.

Ariel's heart slammed against her ribs. No. Not like this. She scrambled backward, her shoulder blades hitting the rough stone of a crumbling wall. She had to find someone. Anyone. A legal shield.

Her gaze darted through the jeering, shoving mass of bodies. She needed someone who wouldn't hurt her. Someone the others wouldn't fight her for.

There.

In the shadow of the wall, isolated by a wide berth of empty space, stood a figure. He leaned against the moss-covered stone, his posture slumped. His face was a sickly pale, almost translucent under the gray sky.

The sick one, the original Ariel's memories whispered. Elvin,Dying,No one wants him.

He suddenly hunched over, a violent cough tearing from his chest. It sounded like tearing fabric. He clapped a hand over his mouth. When he pulled it away, dark red blood stained his long, pale fingers. It