Flames filled her vision, and Ginny Weasley was laughing in the night. Lovely little Ginevra was walking through fire like it was nothing, cackling with malevolent glee.
The opera house, the one she had just set ablaze, was called "Salazar." A monument, really, as it was no longer used for show-seeing or champagne-swirling. The pureblood sects had been using is as a meeting place, what they obviously thought of as their royal war rooms.
Covered in velvet, it was. All green and draping over high walls under vaulted ceilings. The finest silver could be found set upon the theatre seats, used for inlaying the names of important purebloods who had donated money and murder. The stage was the most magnificent display, shining cold and expansive across the hall, but it was not so beautiful before as it was now, with lady Gryffindor dancing across it in a triumphant ballet.
Fire flicked from her fingertips and she stared up at the sky, already visible through the burning ceiling. She waited for it to open all the way, her very own observatory.
From her stage, Ginny could see the stars.
A sudden mirth exploded inside her, and the rebel's mistress began to laugh again. As she flew through the House, she laughed, and sang, and the people of the city outside could hear her madness echoing through the midnight.
The velvet burned, and the townspeople cried, the tassels charred, and the spiders scuttled far away, Ginny trilled, and the birds took flight.
Rebellion's knight could not be stopped. Ginevra, exultant, razed her enemy's pride.
When her work was done, lady Red strode into the city square, and sat upon "Salazar's Throne." The people there just stood and stared unblinkingly at the fearsome woman.
"Give my regards to your king," she said, and disapparated.

Later, when questioned, the witnesses could only say that a most terrifying creature had caused mayhem there that night. Some swore that they had seen a succubus, delighting in the flames. They cried, and screamed, bereft and afraid for their lives, and no one had been brave enough to stop her.
There would be stories written of Ginny Weasley, and they would not be fairytales. No, her stories would be of magic, and maelstrom, and they would call her death-bringer and madness.

Madwoman, indeed.