**Chapter 3: Uncovering the Truth**

"Oh baby, are you telling me lies?" Sirius cooed, his voice low and husky as he pushed his massive cock into Regulus's trembling body. Regulus's eyes widened in shock, his face pale as he stared up at Sirius. Sirius's eyes locked onto his brother's, his expression searching for any sign of deception. He could see the fear and anxiety written all over Regulus's face, and it only fueled his determination to uncover the truth. Regulus's body tensed, his muscles clenched as Sirius's cock breached his defenses. He let out a soft gasp, his eyes welling up with tears. Sirius's grip on his hips tightened, holding him in place as he began to move. "Tell me, Regulus," Sirius whispered, his voice gentle but insistent. "What were you doing, walking around the castle in your...undergarments?" He emphasized the last word, his cock thrusting deeper into Regulus's body. Regulus's face contorted in a mixture of pain and pleasure. He tried to speak, but all that came out was a soft whimper. Sirius's eyes narrowed, his expression unyielding. "Don't play games with me, Regulus," Sirius warned, his voice low and menacing. "I know you're hiding something. And I'll find out what it is." As Sirius continued to move, Regulus's body began to relax, his muscles loosening as he adapted to the invasion. His eyes locked onto Sirius's, and for a moment, Sirius thought he saw a glimmer of something - a flash of memory, perhaps, or a hint of a secret. Regulus's lips parted, and Sirius leaned in, his ear inches from Regulus's mouth. "Tell me," he whispered, his breath hot against Regulus's skin. Regulus's voice was barely audible, a soft whisper that only Sirius could hear. "I...I was meeting someone," he stammered. Sirius's eyes snapped back to Regulus's face, his expression intense. "Who?" he demanded, his voice firm. Regulus's eyes darted around the room, as if searching for an escape. "I...I don't know if I should say," he stammered. Sirius's grip on his hips tightened, his cock thrusting deeper into Regulus's body. "You will tell me," he growled, his voice low and menacing. "Or there will be consequences." Regulus's face paled, his eyes welling up with tears. But Sirius could see the determination in his eyes, the refusal to back down. It was a look Sirius knew all too well, a look that said Regulus was willing to take risks, to push boundaries. And Sirius was about to find out just how far his brother was willing to go.