And now a positively dangerous look crept over Aberforth’s face.
“Grindelwald. And at last, my brother had an equal to talk to someone just as bright and talented he was. And looking after Ariana took a backseat then, while they were hatching all their plans for a new Wizarding order and looking for Hallows, and whatever else it was they were so interested in. Grand plans for the benefit of all Wizardkind, and if one young girl neglected, what did that matter, when Albus was working for the greater good?
“But after a few weeks of it, I’d had enough, I had. It was nearly time for me to go hack to Hogwarts, so I told ’em, both of ’em, face-to-face, like I am to you, now,” and Aberforth looked downward Harry, and it took a little imagination to see him as a teenager, wiry and angry, confronting his elder brother. “I told him, you’d better give it up now. You can’t move her, she’s in no fit state, you can’t take her with you, wherever it is you’re planning to go, when you’re making your clever speeches, trying to whip yourselves up a following. He didn’t like that,” said Aberforth, and his eyes were briefly occluded by the fireflight on the lenses of his glasses: They turned white and blind again. “Grindelwald didn’t like that at all. He got angry. He told me what a stupid little boy I was, trying to stand in the way of him and my brilliant brother… Didn’t I understand, my poor sister wouldn’t have to be hidden once they’d changed the world, and led the wizards out of hiding, and taught the Muggles their place?
“And there was an argument… and I pulled my wand, and he pulled out his, and I had the Cruciatus Curse used on me by my brother’s best friend—and Albus was trying to stop him, and then all three of us were dueling, and the flashing lights and the bangs set her off, she couldn’t stand it—”
The color was draining from Aberforth’s face as though he had suffered a mortal wound.
“—and I think she wanted to help, but she didn’t really know what she was doing, and I don’t know which of us did it, it could have been any of us—and she was dead.”
His voice broke on the last word and he dropped down into the nearest chair. Hermione’s face was wet with tears, and Ron was almost as pale as Aberforth. Harry felt nothing but revulsion: He wished he had not heard it, wished he could wash is mind clean of it.