While rescuing the dragons from a fire in the stables caused by a powerful lightning storm, Astrid suffers an injury that leaves her blind.
- Almost Kiss: When Astrid worries that she may never get her sight back, Hiccup assures her that he'll always be there for her, then leans in for a kiss. Sleuther's impending arrival spoils the moment. Astrid calls him on this later, wondering why he didn't go through with it. He admits that had thought about it before, but never felt the moment was right.
- Badass in Distress: Throughout the episode, Astrid is blinded by the flash of a lightning bolt that indirectly hit her. This causes her to be rather clumsy, such as tripping over rocks, and having to rely on everyone else, and she sounds more afraid than anyone that she won't get her eyesight back.
- Battle in the Rain: The Edge is in the middle of a terrible storm, so they have to do battle with the Sleuther in the rain.
- Big Damn Kiss: After three and a half seasons of Unresolved Sexual Tension, Hiccup and Astrid finally shared one in this series at the end of the episode, which starts their relationship for real. Importantly the difference from their past kisses is that it was a fully mutual one rather than entirely Astrid taking initiative.
- Callback: Just before the Big Damn Kiss, Astrid commented that Hiccup was about to kiss her earlier in the forest. Echoing her Armor-Piercing Question from the first movie, she then asks, "Why didn't you?"
- Disability Superpower: Downplayed. While blinded, Astrid uses her hearing to 'see' what the others can't, picking up on an approaching Stormfly just on her footsteps, and being able to tame Sleuther singlehandedly by confusing it using sound.
- Florence Nightingale Effect: While they were close before, the short period where Hiccup took care of the blinded Astrid eventually cemented them as an item.
- Gilligan Cut: Astrid wants to help find Stormfly, but Hiccup thinks she's in no condition to do so and puts his foot down: she's staying at the base. We get a brief look at a intense glare from Astrid as he says this. Cut to her flying with him on Toothless, and him musing to his dragon that he won't try putting his foot down with her again.
- I'm Standing Right Here: When Hiccup laments his failed attempt at putting his foot down to Toothless, Astrid, who's riding with him, notes that she can still hear just fine.
- Moment Killer: Hiccup's Almost Kiss with Astrid is ruined by the approaching Sleuther.
- Noodle Incident: Hiccup claims that Bucket was temporarily blinded when he was struck by lightning.
- Not Helping Your Case: Hiccup tries to comfort Astrid by pointing out that Bucket went blind temporarily when he was struck by lightning. Using a man who has to wear a bucket all the time as an example does not inspire confidence in her recovery.
- Official Couple: Hiccup and Astrid finally become this by the end of the episode.
- Relationship Upgrade: Hiccup and Astrid start a romantic relationship in this episode.
- Suggestive Collision: Hiccup lands on top of Astrid after she trips on a rock and he tries to catch her.
- Temporary Blindness: Astrid winds up like this thanks to a point-blank lightning bolt. She gets better by the end of the episode.
- Watching the Sunset: A bit higher than is common for the trope, but the sun's nevertheless on its way out when Hiccup and Astrid have their Big Damn Kiss.