Batreaux's House is a location from The Legend of Zelda: Skyward Sword. It is a run down shack built on a wooden platform underneath Skyloft which can be accessed via a ladder inside the Graveyard's shed. It is home to the human loving Demon Batreaux, who is forced to live there due people of Skyloft's fear of his demonic appearance.
Ironically, despite Batreaux's polite and gentle personality, the house itself is not very inviting, as its macabre interior with demonic skulls hang from the ceiling, cobwebs, and scythes on the walls is what one would expect for the dwelling of a demon. The house also lacks furniture such as chairs or a bed. Two portraits of Batreaux hang on its walls and if Link preforms a Roll Attack on the wall, the pictures will tilt (similar to painting of Groose in Groose's Room at the Knight Academy).
It is implied that Batreaux has lived there alone for many years. However after saving the five year old Kukiel from accidentally falling off Skyloft, Batreaux befriended the little girl, who unlike the other residents of Skyloft did not scream in fear at the sight of him. As a result, Kukiel would occasionally go to Batreaux's house to play with him. Happy to have a friend and due to its isolated location, Batreaux allowed her to scream as loud as she wanted when she was at his home as part of their scream-as-loud-as-you-can-game. However this lead to a brief misunderstanding when Link who was searching for Kukiel after she went missing and almost attacked Batreaux, her screams lead Link to believe that the demon had kidnapped the girl. During his first time here (when he stumbles upon Kukiel and Batreaux in the middle of their game), if Link asks Fi for a Hint, she will tell him it is Batreaux's House, but that she does not have enough information to properly analyze the situation. He can also talk to Kukiel, who shows no fear giving the player a hint that things are not what they seem. However Batreaux was able to explain the situation and seeing Link was a noble soul, he asks Link if he would collect Gratitude Crystals for Batreaux to turn him into a human and finally be able to mingle with the people of Skyloft. Since it was too dangerous to go out after nightfall in Skyloft due to monster activity (ironically caused unintentionally by Batreaux's demonic presence) he told Link he would send Kukiel home in the morning but told Link to tell her parents Wryna & Jakamar their daughter was safe. After staying the night with Batreaux, Kukiel returned home the next morning, with her parents who ironically assumed Kukiel's friend Uncle Bats was a kind gentleman who had looked after Kukiel. Link would visit Batreaux's House occasionally to give him the Gratitude Crystals he had acquired in exchange for various rewards.
After Link collects 30 Gratitude Crystals and receives the Big Wallet from Batreaux, a Treasure Chest will appear inside the shack. However Batreaux warns (even forbids) Link from opening it as it contains the Cursed Medal which prevents Link from opening his Adventure Pouch or using any Bottles or Shields as long as it is inside his Adventure Pouch, while boosting his chances of find both Rupees and Materials. If Link opens the chest and takes the Medal, Batreaux will point out that by storing it at Item Check, Link can open his Adventure Pouch.
After Link collects 80 Gratitude Crystals and takes them to Batreaux, he is transformed into a human. Afterwards he leaves finally leaves home and begins to mingle with the people of Skyloft, and starts hanging out at the Bazaar during the day and the bridge at night, due to the monsters having disappeared and Remlits no longer becoming feral, due to the disappearance of Batreaux's demonic aura.
Unlike most houses in Skyloft, Link can use items and his sword while in Batreaux's House, though it severs no purpose. Why this is possible is unknown, however most likely it is to support the illusion that Batreaux was simply another enemy monster during that Kukiel's missing side quest. If Link uses the Beetle he can humorously hit Batreaux with it or use a Bomb to scare Batreaux. He can also use the Gust Bellows to blow wind at Batreaux causing him to brace himself from being pushed back by the wind.