And that was how Iris Lily grew up. For the central part of the lunar cycle, during the rise and descent to, from and including the full moon, she lived at Hogwarts and was taught by the Lords of the Elementals in each separate strand of her power. For the other half, she lived with her godfather and lived as normal a life as she could.
Remus would always marvel as to how such a tiny child could produce such magic. At first, there was no seeming change; she would still attract leaves if she wanted them to come to her, but not much else. Things started to change when she began to walk.
Being more exposed to the elements helped her develop her powers. When she got angry, Remus noticed that things around her seemed to unsettle as well, the wind pick up slightly, or the fire in the hearth would flare. When she was calm, often so was the sea that surrounded them. For fun, she would pick up a pebble and make it levitate in her palm, making it dance across the sky. And each time she returned from her teachings at Hogwarts, her magic would've strengthened.
And, she was always so curious. She had questions about everything, and sometimes he wouldn't even have the answers. She asked about her parents, and her brother, and everything about the Wizarding world she could think of. He answered as best he could; feeling it wrong to deprive the child of the information she craved. And she remembered it all.
"It's his birthday today, isn't it?" Iris asked one summer when she was only about 6 years old. Remus glanced up at the small girl smiling.
"Who's birthday, my dear?"
"Harry's. It is the 31st of July, isn't it?" She asked as she stepped over towards him.
"Yes it is," Remus nodded. "You remembered."
"I seem to remember everything," she smiled, before glancing out over the sea to the mainland. "Except him," she whispered. "I cannot remember him, or my mummy and daddy."
"You were too young," Remus sighed, "you had not yet been tested, so you didn't have your special skills yet." The small girl nodded curtly, absently, before wandering outside. Remus stood and watched her through the window. She ran around, the wind snatching at her hair and clothes. She was happy. The one thing that he refused to tell her was whether Harry was as well. He had heard of Lily's sister's family, and he did not suspect them to treat him well. Although she couldn't remember him, Iris knew and cared for her brother, even at that young age. It hurt him more than he let on. Mainly because Harry thought he was alone.
Until fate thought to reveal her, Iris did not exist.