AN: After many demands for a sequel or an epilogue I have given in to the latter, since the sequel didn't work out when I tried it. Hope you like it and aren't too disappointed!
Epilogue
Almost two millennia had passed since he had last seen them, since he had willingly gone into the rift and woken up in ancient Rome. He had thought about them now and again over the centuries, especially in the beginning and the last few decades, they were the only ones he knew he would see again. He had even sworn he would reunite with them on this very evening. But as he watched from street below he couldn't do it. That life was the past, too long had passed for him to go back to Jack, or Torchwood. He knew too much about them now for that ever to be the same. Jack tried, he really did, but Torchwood was Torchwood. They were hardly the good guys Jack had made him think they were all those years ago. He couldn't go back and pretend he didn't know, that he was the same. He wasn't.
Perhaps he would seek Jack out in a few decades, when some time had passed and when Jack wouldn't expect him to be the same boy he had been when he had jumped into the rift with Hart. What he would however do was go to the hub and take his wand before the others noticed it where he had left it. Two millennia without it had been too long. The first centuries without magic, forced to live one life after the other, being everything from slave to nobleman, to husband, to pirateā¦ always knowing he had the power to do things, to change things, but no access to that means had been worse than anything else he had experienced in his long life, in his different worlds. But he had adapted, as would they adapt to life without him. He hadn't been with them long, not even Jack.
Jack would continue his life, as would Ianto, Owen, and Tosh. And so would he, he had a degree to finish, a daughter to care for, her grandson to watch over, and yet another life to live. And one day that life, or perhaps another one further down the line, would reunite him with Jack. They may not be lovers again, but they would see each other. After all, they had eternity, and right now Jack needed to mourn the man Harry had been, before he could meet the man he had become. And until that day all he could do was wish him luck.
THE END
AN2: Sirius never entered this world! I told you all that unless you were immortal you wouldn't survive passing through the rift, the souls keeping it open would destroy you and force you to join them! That's why Harry never found any hints of him.