Introduction
It was during the First Wizarding War that the room was created. The room was created not by the founders of Hogwarts, like many people might assume, but by an average witch, one with extraordinary skill in magic not found in many others.
The witch's name was Evelyn Lux. She was a single mother, her husband having died a few months earlier by the hands of death eaters. She had joined the Order of the Phoenix shortly after his death in search of revenge for her love's death and in hopes of creating a better world for her daughter, Eleanora.
Evelyn was an extremely talented witch. She had been placed in Ravenclaw and achieved O's in nearly every subject during her years at Hogwarts. Originally she had planned to become Healer after graduating, but the war and the birth of Eleanora delayed her plans. While her husband fought in the war, she stayed home and watched the house and their child. She desperately wanted to be out fighting herself but knew that she did not want her daughter to live in a world with no parents. Therefore, she promised her husband not to fight unless absolutely necessary. She kept this promise even after his death, doing something much more significant than fighting in the war.
Albus Dumbledore knew of Evelyn's talent and called her into Hogwarts a couple months before the end of the war. He wanted her advice on how to keep the students of Hogwarts safe if the castle was ever attacked. She proposed creating a room that would be hidden to everyone except those who needed it, and thus the idea for the Room of Requirement was born.
Albus and Evelyn worked for days in search of the perfect place and spell to create the room. They slowly added more and more additions to the idea, including an exit from the room into the Hog's Head, where Albus' brother worked. The Hog's Head also led into Hogsmeade, a busy wizard town where the students or teachers would easily be able to find help.
In the end, they were only able to find one spell that could create a room like the one they imaged; however, there was a catch. The caster of the spell would be linked to the room for the rest of their and their family's lives. The room would be fueled by their own magic, and they would be connected physically and mentally to the room. They would not be allowed to leave within the limits of the spell, meaning they could never travel farther than Hogwarts. Evelyn was hesitant to perform the spell, knowing that no one other than she or Dumbledore should perform it. While she had no problem linking her own life with the room, she did not want her daughter to be linked to the room. There also seemed to be no way to undo the spell once it was done outside of killing the caster or destroying the room they created completely, which could wind up killing the caster anyways from the link of the spell.
Evelyn had a feeling that Albus had known about the spell all along. He was the type of person to hide things he decided unnecessary to share. Though, she supposed he hadn't hidden it from her, just allowed her to find out the knowledge for herself. Weighing all the options, Evelyn decided to cast the spell. While she did not want to subject her daughter to what would most likely be a lonely, miserable life, she did want to help protect the school any way she could, and she knew she could not ask anyone else to do this task.
The day the spell was to be cast Evelyn brought her two-year-old daughter Eleanora with her to the seventh floor of Hogwarts and down the left corridor. This was the area Dumbledore and Evelyn had agreed on to place the room. Albus was present to assure nothing went wrong with the spell. He looked at Evelyn with what seemed like pity in his eyes, but there was also a hint of gratitude. He could not do the spell himself; he knew he would be needed outside of Hogwarts.
With just a few words, the spell was completed. An explosion of light burst from the wall before them, and Evelyn dropped to the floor in pain from the power of the spell. The light, still connected to the wall, formed into a strand of magic that wrapped around the wrists of both Evelyn and Eleanora. Eleanora let out a sharp cry, feeling a slight sting from the magic. The light vanished from the air, disappearing into either the wall or the girls. Evelyn stumbled shakily to her feet. Her formerly blue eyes shone gold from the powerful magic, and her dark hair changed to a platinum blonde.
"Should we test the room?" Albus asked, helping steady Evelyn. She nodded. The headmaster began to pace back and forth three times before the wall, the method the two of them had agreed on in order to keep the room a secret. After the third pass, a wooden door appeared before them. Albus opened the door, revealing a large library with books covering every shelf. He closed the door, and after a few seconds it disappeared. He paced again and another door appeared, this one made of glass. Behind it laid a garden that would make any herbologist faint. He closed the door again and smiled.
"It seems the spell would be a success."
"It seems so," Evelyn weakly replied.
"I apologize again for asking you to do this."
Evelyn shook her head. "I wanted to do this. My daughter might not get the life I want for her, but I might be able to save lives with this. Besides," she chuckled, "this is my way of helping us win the war without breaking my promise to my husband."
Albus laughed, glad that his friend did not lose her humor to the spell. "I'm not sure this is what he had in mind."