Sirius had pulled a prank, one that got a lot of people hurt. He grew up in an abusive home so he thought he was exactly like his abusers, his parents. Sirius was sat in the library with his younger brother and his ex friends James, Remus and Peter were signing ‘mama’s boy.’ Since Sirius could understand sign, he knew exactly what it meant. It hurt as it confirmed his fears but he had to deal with it.