Ursula Undertow wanted a tattoo she could not buy. She had crossed three trenches to reach this reef tribe, chasing a promise she made to herself: to earn a sacred mark from every hidden mer-tribe in the drowned deep. Each tribe inked its own story into a stranger's skin, but only for those who proved worthy. Now she hovered at the edge of their coral homes, empty-handed, her pastel rainbow tail catching the light while a row of guards watched her with hard eyes. A broad merman blocked her path. He crossed his arms and spoke without warmth. "Strangers come with gifts or they don't come at all. What do you carry?" Ursula opened her hands. Nothing. No pearl, no rare shell, no stolen treasure. She had traded her last pearl two trenches back for safe passage. "I carry only myself," she said. The guard turned away. That answer sent travelers home. Then a voice cut through the water behind her. "She carries more than that." Ursula spun. A tall merman drifted closer, blonde hair loose, tattoos winding down both arms, his tail deep blue and teal. Marshall Mako. She had heard his name in every port bar in the trenches. He collected sacred marks too, and he never lost a trade. She had hoped to reach this tribe before him. She was too late. "Stay out of this," she told him. Marshall grinned and ignored her. He faced the guard. "You want a gift. She fixed your east current gate on her way in. I watched her do it." He nodded toward the reef's outer wall. "Your children were caught in the pull. She freed them and lashed the gate shut." The guard's face changed. He glanced back at two small mer-children clinging to a rock, safe. Ursula had not thought twice about it. She had seen them thrashing in the current and simply acted. She had not known they belonged to this tribe. "Is this true?" the guard asked her. "Yes," Ursula said. The guard studied her a long moment. Then he beckoned. The row of guards parted. Inside their gathering circle stood a tall carved totem, covered in coral fish and a smiling octopus and bright sea glass. An elder pressed a bone needle to it, then to Ursula's shoulder. The mark bit into her skin, cold and sharp. When the elder finished, a fish curled along her arm in blue and green ink. One tribe down. Ursula turned to leave and found Marshall waiting. He had helped her win the mark she came for. That was the problem. "You owe me now," he said. "And I want the next tribe's mark before you get it." Ursula's stomach dropped. She had crossed three trenches alone. Now she had a rival at her side, and a debt she never asked for.