Draco Malfoy looked fondly at his granddaughter snuggled comfortably in his chest. Her body had formed a warm blanket on top of him. It had taken him quite a while to see her eyes finally shut. Hermione was her name after her grandmother, his wife. The rain was pouring outside, battering the windows and knocking on the door.
The room suddenly darkened with a quick "Nox" and a wave of his wand. A long day it had been for him, and yet he still had time to tell his beloved Hermione a grand story to answer her spontaneous question: "It's not really raining cats and dogs, is it?" She had overheard her grandparents speaking of the weather after she and her papa came back from the park, soaked. Draco had happened to use that particular adage.
"No, poppet," Draco answered, "it is a saying from long ago and quite an interesting story to go along with it." Hermione probably didn't hear a word he said except for story, because she settled herself on her grandfather's lap before he could say otherwise, and his oral legend had begun.
Long ago, in a Muggle city near London, there lived a witch. The problem was that she didn't know that she was a witch. Strange things would happen in her moments of strong emotion, but never could she figure out why. Muggles will look for any excuse of an occurrence besides magic. She first thought it was the wind when her kitten flew from the tree that had taken it hostage into her arms. Apparently, sun was responsible for her dog's new lighter fur color after the neighborhood boys had dyed the poor animal's fur a deep black.
This witch, as you could probably tell, was an extreme animal lover, and was also very hated by her city. They simply would not believe that she didn't do any of this. Hence, they would mess with her beloved pets, her only friends. Even her parents were ashamed and only offered her shelter, food, and a bathroom; all she would need for basic survival.
She absorbed every insult, every blow to her pride, and stored it in her body. She knew that if it didn't find a release, all would come out at once, the results catastrophic. Her magic began to spurt at intermittent moments, in school or at home. The townspeople grew very afraid of her power and sent her away to America, bound and chained on an airplane in the storage hold. All her friends were on that plane with her, the cats and dogs. The hatred she felt at her parents and the people of her town added in the ever growing power inside of her, creating power for the ultimate revenge.
Those silly bounds and chains broke easily when she focused this newfound strength. She freed her companions and they climbed up to the pilot's cabin in the plane and took control. The revenge and power this witch was feeling was unbearably strong and she couldn't control it. Those people in that city would pay for their dimwittedness. Their feeble attempts to be rid of her had only increased her need to dominate them.
The witch flew that plane right over her town, performed some 'special ness' onto her followers, and pushed them from the plane. Her 'special ness' would stop them from falling to their deaths.
It was noon in that town and everyone was inside, for it was a stormy day and it was lunchtime. The people looked out their windows and saw the witch's pets pounding to the ground, only to be uninjured when they arose. Those townspeople fled to nearby cities soaken wet screaming, "It's raining cats and dogs!"
Of course, nobody believed those people and had an inside joke now that they would pass down to their children. Every time the rain was particularly vicious, they would say that line. The witch decided that with her power she could do anything and thus, sent down murderous rain during a rainstorm over those townspeople and their descendents now spread across the world.
Draco was greeted with a nudge to the back by his wife as they looked upon their sleeping 4-year-old granddaughter that sometime during the story, fell asleep. Draco and his wife were tired as well and fell asleep, all three of them, on Draco's lap.