A/N and Disclaimer
Last part, thanks for stickin' around guys. I don't think I have to explain what happens in this part. And one more time, I own none of the characters. The lyrics below are from "Some days" by Regina Specktor, which is a heartbreakingly lovely song. Also, reviews are love, spread it around.

1996
Some days aren't yours at all,
They come and go as if they're someone else's days
They come and leave you behind someone else's face
And it's harsher than yours, and colder than yours
They come in all quiet, sweep up, and then they leave
And you don't hear a single floorboard creak
They're so much stronger than the friends you try to keep,
By your side...

"He can't come back, Harry." He'd heard himself say, his voice breaking, "He can't come back because he's d-" But the rising thickness in the back of his throat had cut him off then, and he looked away.
Number 12 Grimmauld Place was empty when Remus arrived, and dawn fast approaching. The first few rays of sunlight stretched themselves out across the kitchen floor. On the counter there were still two cups of tea, cold and untouched. He felt his stomach lurch, the lump in his throat rising as he sat down at the table, his hands shaking unsteadily.

He knew he should go upstairs, straighten things up and pack his few belongings. He knew what was there. An unmade bed, Sirius's wrinkled shirts, a few of his own probably tucked into the dresser or thrown under the bed.

Remus let out a few quiet sobs, one cold hand on his forehead and the other gripping the edge of his chair. His head throbbed. He thought of Sirius. Of just yesterday when he'd made them breakfast, of August when they'd gotten sopping wet out in the rain, of all those years he'd been gone, leaving Remus to fill in the gaps and slowly move on by himself.

He wasn't sure he could do it all over again.

He wiped absentmindedly at his tears, soaking the edge of his shirtsleeve in the process. Daylight was flooding into the empty house, warming the chilled air. Remus wondered, for a moment, what Sirius had said when he'd seen James again after all these years.

When he finally climbed the stairs around noon, he pulled on one of Sirius's old shirts and fell asleep in the unmade bed.

Tonks was making lunch when he came downstairs the next day. He had thought, vaguely, that it was Sirius making all that noise downstairs, but then remembered why his pillow was wet and his head still hurt.

She nodded briefly when he came into the kitchen and poured him a glass of water. He took it, gratefully, and found himself some aspirin in the cupboard.

"Dumbledore's coming by later, thought you might want to know." She offered.
Remus shook his head. "I'm leaving tonight. I'm not staying another night here. I've just got some things to pack before, that's all."
Tonks put one hand on his shoulder "Remus, if there's anything I can do…"
He gave her a grim, half-hearted smile. "I'll be fine. If I know how to do anything, it's grieving."

At the bottom of his suitcase Remus Lupin carried three photographs. One of James and Lily, the day they got engaged. One of Him, James, Peter and Sirius on their last day at Hogwarts, taken on the castle's front lawn. And one of him and Sirius, standing in front of their flat, in which Sirius has his arms wrapped around Remus's waist and they're both laughing.

He folded a couple of Sirius's shirts on top of them, and then his own clothes. He piled his books and other belongings on top of that, and then closed the lid. It felt like he was closing a significant part of himself as he closed that lid, and then closed the door to the room behind him.

He kissed Tonks on the cheek before he left, reassuring her that he'll be fine. She wiped at some of her own tears, and laughed, feeling foolish, because she didn't really get a chance to cry yesterday. He nodded at Dumbledore as he left, knowing he doesn't have to say a word because the old man already understands.

There's still a war to fight, and Harry is still his best friend's son. He has an obligation, and a very mismatched family to protect within the Order.

And so Remus Lupin moves on, because it's the only thing he can do.