Dragons are often dangerous creatures with the exception of Spike. They have the ability to breath fire and can create smoke when they snore, though the latter ability is most likely an unintentional one. Spike, on the other hand, can use his fire to send scrolls directly to Princess Celestia. Most dragons live in caves filled with gems, jewels, and other precious treasures. Dragons love to feed on and eat gems.
Depicted in the series
In the series, dragons are depicted as creatures that hoard jewels and other rare materials to make beds, in the series the more things a dragon has, the bigger and greedier it gets. this process is shown in "the secret of my excess" where the events are seen in process. The two dragons that appear in the show besides spike have been sleeping until a character wakes them up, the dragons mentioned earlier have been shown to have the ability to speak english (like spike can) but only the green dragon and spike were shown to be able to breath fire, but the red dragons smoke was enough to destroy the rock fluttershy was hiding behind and send the other five main characters into temporary shock