The Serpent King's Sacrifice

Elderly widow's seven sons vanished. She rescued a golden toad, guided to save the White Serpent King, chained by Wade, losing its Inner Cultivation Core. Nursed the Serpent King. Serpent King found six sons' ashes. Seventh son missing; relics found. Widow grieved. Moved, Serpent King gave up Cultivation Power, became Kai Wren, her seventh son. Lived with her, calling her "mother". Years later, the old woman passed. Kai Wren buried her, stayed alone, calling "mother".