Disclaimers.

Toothless is as much a part of the How to Train Your Dragon movies as Hiccup is, but in the movies we do not get to see the story as much from his eyes. How was he feeling while Hiccup was out being trained to kill dragons? What was Toothless's past? Why was he a bit of a dragon outcast?
Here is the story in Toothless's point of view.