**Chapter 1: A Disturbing Discovery**

Sirius Black had always been protective of his younger brother, Regulus. Despite their vastly different personalities, Sirius had always tried to be a good big brother, looking out for Regulus's well-being and making sure he didn't get into too much trouble. So, when he heard from one of their friends that Regulus had been walking around his dorm room in a thong and t-shirt, Sirius's instincts kicked into high gear. He couldn't believe that Regulus, who was only 15, would be so reckless and provocative. Sirius had always known that Regulus was a bit of a free spirit, but this was taking it too far. He decided to pay Regulus a visit, to put a stop to this behavior and make sure his little brother wasn't getting into any trouble. As he arrived at Regulus's dorm, Sirius knocked on the door, but there was no answer. He tried the handle and found it unlocked, so he let himself in. He called out, "Regulus, it's me, Sirius. I need to talk to you." He followed the sound of Regulus's laughter to the common room, where he was shocked to see his little brother sitting on his friend's lap, wearing a thong and a tight-fitting t-shirt. Regulus's friend, a boy a bit older than Sirius, was stroking Regulus's thigh, and Regulus was sucking on a lollipop in a way that was far too suggestive. Sirius's eyes widened in horror as he took in the scene. He felt a surge of anger and protectiveness, and he quickly moved to intervene. "Regulus, what the...?!" he exclaimed, trying to keep his voice calm. Regulus looked up, startled, and their eyes met. For a moment, they just stared at each other, and Sirius could see the guilt and embarrassment written all over Regulus's face. The friend, on the other hand, just smiled and continued to stroke Regulus's thigh, as if he had no right to be there. Sirius took a step forward, his fists clenched at his sides. "Get him off you, now," he growled, his eyes flashing with anger. The friend, seeming to sense that things were about to escalate, slowly stood up, still holding Regulus's thigh for a moment longer than necessary. Regulus looked up at Sirius, his face bright red, and mouthed "Sirius, please..." but Sirius just shook his head, his expression unyielding. The friend finally released Regulus and stepped back, a smirk on his face. "Hey, no need to get violent, Sirius," he said, holding up his hands in a gesture of innocence. "We were just hanging out." Sirius's eyes narrowed. "I don't think you were just hanging out," he said, his voice low and menacing. "And I think it's time we had a talk, Regulus. In private."