Dragons are feared creatures, portrayed as horrific monsters in every bedtime story that ponies have known from birth.
Spike is a dragon. And as time goes on, he grows more acutely aware of his monstrous side and wonders if the fabled beast is all he is meant to be.
His fears come to light one day while he his helping Rarity collect some gems. The two are attacked by a rogue Diamond Dog and Spike, acting in fear and anger, kills their attacker. Horrified at his actions, he flees into the Everfree Forest with the rest of the monsters. Now, it is up to Twilight and Rarity to find him and bring him back home, if they can prove to him that he is not the monster he believes himself to be.