Tear Jerker / Gift of the Night Fury

• When Hiccup builds Toothless a completely working tail. When Toothless realizes he can fly independently, he backs away from Hiccup and takes off.
  • ...leading to a different kind of tears when he comes back with Hiccup's helmet and destroys the new tailfin, instead insisting on the original saddle and rig that requires boy and dragon to work together.
  • Hiccup's obvious hurt at Snoggletog after he's brought all of the other dragons home, but Toothless is still missing. He even miserably asks Astrid where on earth Toothless could have gone. Given that Toothless was his first proper friend, you can see him wondering whether Toothless stayed out of real affection or just because he needed Hiccup to fly.
    • A subtle moment when Hiccup thinks he hears Toothless on the roof, and rushes outside to see him, but he's not there. To make it worse, just like at the beginning of the story Hiccup slips on his prosthetic leg...but unlike the first scene, Toothless isn't there to catch him. Just a painful reminder that he may have given Toothless the means to survive on his own, but Hiccup is still very dependent on his dragon.
• After all of the dragons have left, the children sadly build a snow Gronkle and tearfully hug it.
• When Hiccup gets back to Berk, and everyone start to bombard him with questions.
  "Why did they leave!?"
  "What if they never come back?!"
• Astrid pleading with Stormfly not to leave.
  Astrid: No, no, no! Don't leave Stormfly! Don't go!
• It is very probable that the reason Toothless doesn't join the other dragons is because he is the last of his kind. There is no dragon for him to mate with.