I did warn you. Prepare for mushiness...

Time stopped for the dragons in their slumber and barely a minute after he shut his eyes he opened them once more to find the boggy land to have risen once more, the centuries of mud encasing him. As he broke through, he spotted something that made his heart leap, there, in the distance, where the tribe had once stood, a single plume of smoke was rising again. Another one of his kind crowed in the distance and toothless returned the call happily. The time of Dragons had returned once more.

He didn't know how many millennia had passed since he had last been awake, but by the bits and pieces of rubble he could see, buried in the mud he summed that by now settlements had risen and fallen long ago.

He galloped towards the smoke, only to see a group of humans heaving heavy wooden beams across the ground, assembling new buildings. They cowered away from him as he ran up to one of the newly assembled houses, right on the place where his old home had been all those years ago, and to his delight saw a familiar fat old man and a young boy sitting at the table. This wasn't Stoic the Vast and Hiccup, no, but by the looks of them they could be. The boy's head hair was a mess, a worried expression seemingly a default look of his. He and his father stood as the Dragon sheepishly through the door, holding a fish he had stolen from another house held in his mouth. He set it on the table and nuzzled the boy's arm.
They looked at each other and the memory of past lives rekindled.
Dragons could sense their masters from miles away and there were old tales of dragons sensing their dead masters in new-born babies. Of course, Toothless had never believed them; yet here he was, looking at the boy like he had known him for a thousand years.
"T-toothless...?" The boy guessed, seeing the Dragon's mouth.
Toothless smiled, that was all he needed to hear. His Hiccup was back, new face but same soul, and he was glad to see him again.