The story
Ninety nine sacred cores, and he put one through her heart.
Layla spent a whole life collecting them so her contracted beast, the Sacred Whale Neil, could take human form, and the moment he had it he pierced her heart and pushed her into the Bloodtide Trench. Reborn on the day of the contract ceremony, she leaves him standing and picks a dying little spirit snake instead. Neil teams up with her sister Evelyn to make her look ridiculous for it, and then the snake turns out to be Poseidon, the Sea Emperor.