Waking up at 12 Grimmauld Place wouldn't have been something concerning except for a few things.
1. Harry had fallen asleep in the Eighth years' dormitory. 2. He wasn't even in the right bedroom at Grimmauld Place. 3. Sirius Black was standing right in front of him, looking very much alive.
(Until AO3 can get their servers together again, use the FicHupe to download it; there is https://www.wattpad.com/story/2395150... but that only shows the first couple of paragraphs of each chapter, grr…)
This story leans a bit too much into the Drarry instead of into the plot, to the point of forgetting to explain the whereabouts of Snape near the end, though I can guess. It’s otherwise solid and made me laugh enough for a fiver, but this gets a downrating.
I am weak for a good HP time travel-fix it and this was that. Really interesting way of explaining the time travel itself too. Consistently well written.