Sirius clung to Regulus like a lifeline, some of the tears he'd been trying to hide escaping to stain his brothers robes.
"Dumbledore never tells anyone anything," Sirius whispered, voice damningly choked up. "I thought you were dead for seven years. It, it killed me. I know we don't always get along but Reg, Regulus, you're my brother. My baby brother. I thought I failed you. I thought..." he couldn't continue or he would completely melt down. He simply chose to hold him tighter, letting his solid presence wash away some of the hurt of the last few decades.