Let me give you a little background about Agraria's history with dragons. There were originally dozens of dragons scattered throughout the continent, designed to protect and help the citizens. Since they could live 200+ years, they were usually very wise and insightful along as being skillful protectors. However, they ended up isolating themselves from the people they were supposed to live alongside with, and began fighting among themselves. In fact, the cave Selina is from was originally a den for a few dragons before they ended up turning on each other. Eventually their numbers dwindled. These days, no one has seen a living dragon in over one hundred years and it's assumed they all died out. So a living, breathing, vicious dragon showing up out of nowhere is rather unheard of.