I'm feeling nostalgic for HTTYD1, okay?
If you don't get the title, read the books. How to Ride a Dragon's Storm, specifically.
Personally, I'm not a fan of the Hiccup-long-coma theory. For some reason, I'd always assumed that he woke up the next afternoon (which is rather foolish of me, but headcanons are hard to shake), but this is some exploration of how it probably went.
Hiccup sleeps for a long time.
Toothless doesn't understand.
Really. Sometimes, before everything changed, Hiccup slept with him at the cove, and he always woke up at daybreak, after hours, not days, just as any dragon does.
But it's days he sleeps now.
Toothless can smell the worry and fear on every human who comes in the house - Stoick, Astrid, an old, wrinkled woman who smells like plants, a big yellow-haired boy, a short brown-haired boy, and a female and male who smell and look enough alike that they must be from the same litter, the last four of which almost always come together.
Hiccup doesn't smell worried or afraid, though.
He smells sick, sometimes, when his neck and cheeks and forehead become red. He smells bloody and infected sometimes, when Toothless alone is the first one to know that the stitches aren't doing enough to keep the Hiccup in and the world out. He smells tired, most of the time, which is confusing because all he does anymore is sleep.
But overwhelmingly, he smells stale. He doesn't sweat or move. He doesn't wake up or laugh or crinkle the corners of his eyes and smile in the way Toothless likes so much, or walk or run or fly. He just lays quietly and still, not dead but not very much alive either.
Toothless doesn't leave the house once. He stayed awake for the first three days but finally napped, and he still has a hard time forgiving himself for that.
The smell of Hiccup in his loft upstairs is stale, too. The place where his bed - now downstairs, with Hiccup in it - used to be smells unslept in, his chair smells unsat in, and his papers and sticks of charcoal smell dusty and unused.
But no matter where Toothless is in the house - curled up around Hiccup's bed, hanging from a ceiling beam, lying practically in the fire for warmth - his acute, excellent, and sensitive Night Fury hearing hears the sound of Hiccup's quiet, steady breathing.
Maybe the humans get worried that Hiccup might not ever stop sleeping - and Toothless himself has no desire to stop his fretting - but Toothless knows he'll pull through.
If anyone breathes so regularly and determinedly for so long, it has to be doing them good. His stubborn breathing will heal the hurt, shiny marks on the skin of his face - burns, he heard Astrid call them; it will help seal the lumpy red stitches on the stump of Hiccup's left leg so Toothless doesn't have to smell his blood anymore, and it will bring back normal color to Hiccup's white face.
As long as Hiccup breathes stubbornly, he's alive. And as long as he's alive, he's still fighting.
He'll wake up and laugh and crinkle the corners of his eyes and smile in the way Toothless likes so much, and he'll walk and run and stumble and fly again.
Humans are anxious, but dragons are patient, and Toothless will wait.