Written for the Alternate Universes Challenge (89. Crazy for freedom- Write an AU in which Bellatrix rebelled against and rejected Blood Purism in her youth), The Ultimate Patronus Challenge (H23) and the Marathon Competition (Starting point, Prompt: Cheering)
This is a multi-chapter fic. It will be updated.
"I am a Slytherin, you stupid lump of fabric!" Bellatrix Black thought haughtily, tossing her hair back over her shoulder.
The hat seemed to chuckle in her mind, enraging the girl even further. "Hurry up and sort me! You are wasting my time!"
The hat took its sweet time looking through the rest of her memories, rifling through childhood falls and fights. "Yes, you do have potential in Salazar's house, Miss Black. However, there is more than one house that you can fit into."
Bellatrix scoffed but the hat continued, "I can see loyalty in you: to your family and the purity cause, regardless of how wrong it is. You believe in the views of your society, don't you? Yes, you do have the Hufflepuff loyalty, though I cannot see their open-mindedness and skill of toil for you. However, those are all skills that can be developed."
Bellatrix, who had been sitting on the stool in a stony silence, burst into vicious complaint. "I am a daughter of the ancient and most noble house of black, not some duff. You insult my honor and my pride, you foolish piece of clothing!"
"Yes, I can see Hufflepuff may not quite be the fit for you, though I stand by what I previously said: you would do well in a house of loyalty. Ravenclaw is also out; you possess an intelligence that will be be suitable for whatever path you decide on, yes, but you do not crave knowledge for the sake of knowledge."
Bellatrix did not dignify the hat with an answer, but instead chose to stare out into the great hall. Three minutes had passed. She was almost a hatstall.
"And finally, Gryffindor," The hat mused. "Gryffindor would be a good fit for you, Miss Black. You charge after the things you want, often without thinking things through."
"If you send me to Gryffindor," Bellatrix vowed, "I will set you on fire. I am more than capable of it."
The hat laughed, not seeming the least bit bothered by the downright murderous witch plotting his funeral. "What a Gryffindor thing to say, and yet, in such a Slytherin way. Your family has done a very good job teaching the methods of revenge to you."
"I will give you the house you want, but do not forget what is important in life, Miss Black. Slytherin is the house of ambition, cunning, but most importantly; power. Not blood, not family legacies, not money. Power."
"Yes, yes. I am well aware." Bellatrix said, dismissing the hats words with an impatient wave of her hand.
"SLYTHERIN!" The hat called, sealing her fate.
(Across the hall, a house clad in silver and green started cheering. Their queen was back, even if they didn't know it yet.)