Astrid Hofferson (or just Astrid) is the tritagonist in How to Train Your Dragon and the secondary tritagonist of How to Train Your Dragon 2. She is Hiccup's friend and love interest. Astrid is strong and tough, and embraces the Viking way of life and lifestyle. Because of her tough ways, she is extremely difficult to impress and very competitive, often becoming jealous of being out of the limelight. Though she is tough on the outside, once befriended, she can be a loyal ally and a kind friend. She loves Hiccup as her boyfriend.
Astrid is first seen in the film while fighting the dragons that attack the village. Hiccup, the outcast of the village tries to get closer to her, but she quickly dodges them, such as when he requests to share the dragon guide. During another training session where Hiccup fails again, Astrid criticizes him and forces him to choose a side in the war of Vikings vs dragons. She often sees Hiccup slipping away after classes, but doesn't know what. For the next few classes, Hiccup progresses in dragon combat by disciplining the dragons, getting much more popular than Astrid, making her jealous. Astrid attempts to find out what Hiccup's secret is; she catches Hiccup with his dragon friend, Toothless. She at first wants to tattle on him, but Hiccup convinces her that Toothless is different than the other dragons, by taking her on a flight. Astrid gets fascinated by Toothless' flight and even witnesses the truth about the dragons. They steal food from the village to feed a volcanic dragon that will eat them if they don't follow its orders. When they get back, Astrid hits Hiccup for 'kidnapping' her. Then kisses him for the "Everything Else".
Before Hiccup's true Viking test, she promises Hiccup to protect Toothless at all costs. But during Hiccup's battle, Toothless barges in to protect Hiccup getting himself captured and used as a guide to direct Stoick and the other Vikings towards the dragons' nest. After that, Astrid asks a disowned Hiccup why he didn't kill Toothless in the first place, and Hiccup explains that it didn't feel right for him to kill. Then Astrid convinces him that he's the first Viking to ride a dragon, sparking him to save the day. Astrid even assists in teaching the Viking classmates to be gentle with the dragons. She helps battle the volcanic dragon, along with the Viking classmates. But when Hiccup gets seemingly killed in an explosion, she and everyone else see that Toothless wrapped him under his wing.
Astrid then appears the congratulation of Hiccup, who has lost his foot. She hits Hiccup for scaring her, then kisses him on the lips for saving the Vikings and the dragons. She and Hiccup are now a loving couple and they both fly dragons together.