Write a story that seems normal on first sight , except for one small detail that makes it extremely creepy on a more careful reading [ WP ]

Joan and her brother always ran off into the forest behind their house as soon as they came home, picking up sticks along the way. There among the tall trees, they ruled a kingdom together. Father had helped them build a treehouse a year back, and since then the parents had enjoyed a calm summer, the kids having fun by themselves. In their kingdom, Joan and her brother ruled as king and queen, fighting many great enemies. Their imagination fuelled them, as sticks became swords and rocks became trolls. Joan had become fair, her hair bleachedfrom being in the sun all day, and her skin freckled. For hours they'd be out, only returning when Father called them in for dinner or bedtime. 
 
 In their kingdom, the king and queen did not only face challenges in the form of enemies like rivalling kings and forest trolls, but also much simpler things like disagreeing. They argued sometimes, hopelessly trying to set rules and laws that they both agreed to. For instance, her brother had insisted that he as King should always have the sharpest sword, because a King would wield a greatsword with no like. Joan, a bit of a tomboy, also wanted a greatsword to fight trolls with, but such things were not fit for a Lady, brother would say. Over time, their kingdom suffered from these disagreements, and enemies took over lands and castles were lost. Soon, they lost their friend, a great guardian and companion Spot. He was a direwolf with no like, and the inspiration to their noble banners. The trolls took him, throwing large rocks at the wolf until his strength faded, and his eyes closed. 
 
 Joan soon faced the ultimate betrayal, when a rivalling king had come up with a grand scheme. By going behind her back, her brother and the rival king had conspired to usurp Joan's half of the kingdom. Betrayed, Joan could only stand by and watch as her forces and lands were crushed and captured. She began crying. The king, her brother and their forces surrounded her - laughing as they drew their swords. They took turns stabbing her. Her brother's blade, the greatsword, was indeed the sharpest in all the realm, because his blade cut the deepest, and hurt the most.
