In Dragon 1, watching Hiccup befriend Toothless, the Night Fury dragon, is a great storyline. I love smart kids, or young adults in this case, and Hiccup and his friends are a treat to watch. Hiccups affection for Toothless is perfect. Not overdone.The whole story of the human Viking relationship with the dragons is what made this movie so wonderful to me. Read the plot here at Wikipedia.
In the second movie, all is well on the island of Berk, with dragons and Vikings getting along just fine. The conflict comes from an outsider, Drago Bludvist, (don't you love these names?) who is forming a dragon army. I'm going to stop here with the plot so I don't spoil it for you. In fact, I can't even tell you about the romance because it's kind of a surprise. Let me just say, it's sweet and one scene coaxed a few tears from my eyes. Not what I was expecting.
Dragon 2 is a little heavier than the first one, but still enjoyable, especially if you love a good, mushy romance. Be warned, a few more tears were shed by this tough girl when one of our beloved characters runs into danger, so keep the hanky ready. Good movie, just be prepared for a change of tone from the first one.