They made the vow just after sunset, when the river looked like a path of blood and the sky held its breath.
Lina and Joel stood at the edge of the Ilemba River, their fingers entwined, hearts pounding in rhythm with the flowing water. They were young, barely twenty, and convinced the world had never seen a love like theirs.
"Are you sure?" Lina asked, her voice trembling slightly, though her eyes stayed locked on Joel's.
Joel nodded and pulled out a small, worn knife from his pocket. "Forever, Lina. I swear."
They each pricked their thumbs, letting the blood drip into the water before pressing them together. The river accepted their offering with a subtle ripple, like a secret handshake.
"I swear to love you, only you, until death and beyond," Joel said.
Lina smiled through tears. "And I swear the same. May the river bear witness."
They sealed it with a kiss as the last light of day died behind the hills. What they didn't see what no human eyes could, was the shimmer beneath the surface, the slow awakening of something ancient, something that had slept under those waters for over a century.
The River Spirit had heard.