Yes, it's only a one-shot, but better than nothing, no?
MMMMMMMMMMM
Beyond the veil
Sirius stared at Bellatrix Lestrange.
He couldn't move, the smile frozen on his face, eyes wide with shock. She would kill him... now...
He felt smooth cloth brushing against him, and he wasn't afraid of being killed anymore.
His heart stopped dead. Nobody could kill him now. He had just fallen through the veil.
He hoped so much the stories weren't true and he would just fall through the veil, hitting the ground on the other side, still in the hall, Bellatrix coming into sight again and he able to defend himself... But he knew this wouldn't be the case.
He had not died, but just fallen into the never-never-land with no chance to come back.
He could hear whispers and through them, he heard someone scream "Sirius!"...
Harry! Harry would be all alone now. No. He had to go back. He struggled to stop himself from falling, but he only crashed onto white marble. Everything in here was white. It hurt his eyes and Harry's voice faded.
Sirius stood up and stared at a white veil in front of him, tried to touch it, but something stopped him. He knew he couldn't go back...
He turned around, panic in his eyes, with now me James'.
"Don't try to go back, mate. It's no use. Don't you think we tried it for years? Moony will take care of him, as will Albus and Minerva, not to forget the parents of his best friend. You can have a close look at him, but can't help him with anything."
Sirius turned to the veil, but it was gone. His only connection, the only possible way back to Harry and the others was gone.
He turned around to yell at James, that he hadn't tried hard enough, but closed his mouth when he found Lily next to James, tears in her eyes.
"Now Harry's lost you, too. But he'll be fine. Sometime he'll be fine again."
"He never was since you're gone"
Lily stared to the ground "He'll be fine, Sirius, just believe he will... You can't do anything for him anymore..."
Sirius fell down to his knees. Harry would go for Bellatrix now.
Hopefully, she wouldn't kill him. But deep in his heart he knew, secretly he wanted her to kill him, to send him over to him. He didn't want to be separated from the one and only he loved.
But Harry didn't come.