Severus arched an eyebrow. "Albus was well aware that your brother had a vicious streak that went beyond schoolboy bullying so he likely believed that it wasn't out of the realms of possibility. Still, he could have called for a trial for your brother in front of the Wizengamot, if he'd wanted. It was just more useful for him not to."
He actually chuckled at that. "No, Horace never wanted the Headmaster's job. Too much work. He was more annoyed that he'd ignored me after I graduated. He pulled me into the Slug Club because he thought I'd go on to become the next great Potions Master. A mere Hogwarts teacher was of no use to him. But the Headmaster and, in the climate at the time, the Dark Lord's Most Favoured - that was an opportunity for him and I made it plain that he'd missed it." He smirked a little. "I did gain some excellent wine, whiskey and other tidbits out of his attempts to curry favour though."
He tapped his fingers on the table. They were less stained than usual. His work as Headmaster had left him less time to brew and the stains from the ingredients had almost worn off. "Albus didn't crave power. Not in the way you're thinking. Skeeter's books are usually drivel but I think she got closer to the mark than normal with the one about Albus. Much of what she wrote in there made things I'd observed in the man make sense. He was more ruthless than most people realised and he was a chessmaster. We were pawns to him and he would use us - and himself, as his death proves - however was needed to defeat the Dark Lord with little to no concern about our feelings on the matter."
He snorted sourly. "I suppose a backlash by Muggleborns and some halfbloods was inevitable after the war. Even more so if the only voices speaking against them were pureblooded ones.