Complex sentence: Striking, energetic and tough, Astrid is Hiccup's close friend (and love interest), the second-in-command of the Dragon training gang (next to Hiccup) and, like him, tells others what are they going to do.
Split into simpler sentences: Striking, energetic and tough, Astrid is Hiccup's close friend (and love interest). She is the second-in-command of the Dragon training gang (next to Hiccup) and, like him, tells others what are they going to do.