The river serpent... chuckled. Ripples ran down its body and the soft susurrus of shaking reeds filled the air. "Over, under, ridge... But you're too young to cross my bridge." A serpentine arc flooded the bridge, and the head dropped down past the girls' knees. "Beyond the bridge is not for ones as as little as these. Unless the shadowbinder knows, permits and sees."

Rising again and passing so close that the girls could have felt its breath, if it had any, it rippled again. "Or, prove you can. Maybe the bridge is yours to cross. Test my will and I test yours, I test your skill and you test mine." It rose further, and a cobra-like hood spread out in a full hemisphere from the creature's 'neck'. "Which among you would stop a river's flow?"

[@Pseudo Stygian][@Stern Algorithm]