Remus stared beyond the veil, beyond the veil from which Sirius had just gone. If he weren't holding Harry back, he would be gone, too. Gone just like the rest of them.
But he couldn't condemn Harry to death. And so he held the boy back, and the boy unknowingly held him back.
"He's gone," Remus said, telling himself as much as Harry, because neither could accept it, neither could accept the truth. Neither could accept that Sirius was gone.
And Harry had burst out of Remus's arms, chasing after Bellatrix, and Remus couldn't find it in himself to go after him. Instead he stood, staring, beyond the veil, listening to the whispers. The whispers called to him. He only needed to step forward to hear what they were saying…
But he couldn't. Because he was a coward. And he knew the others, the Order, the students he taught, Sirius and James (had they been alive) would disagree. But he was a coward. A monster and a coward. So he stared after his best friend, gone, gone forever, gone beyond the veil.