Faelan heard it too, saw the same heartbreak and hope on Gaius' face, and didn't know which one hurt worse. Gaius stood frozen, looking as if he might collapse any minute, and all Faelan could do was mutter "Sirius!" and run to the door.
It mustn't have worked! Sirius had come home and it was all a mistake. He was never meant to be behind that veil at all, and it wouldn't let him and now Faelan could slug him and hug him and forgive him.