Astrid and Heather's Relationship

"Thanks, Astrid. It was nice having a friend again"

- Heather to Astrid

After a rough start, Astrid and Heather became best of friends and in Dragons: Race to the Edge, they occasionally tease each other about boys, specifically about Fishlegs and Hiccup. Heather knows how much Astrid cares about Hiccup and knows that the two are perfect foe each other. Astrid is very understanding about what Heather is going through and doesn't hesitate to be her friend.

Heather Report, Part 1 and Heather Report, Part 2
In Riders of Berk, Astrid and Heather did not get along well at first as Astrid had evidence that Heather was a spy for the Outcasts and believed that she had bad intentions. However, they made up in the end as Astrid had discovered that Heather's true intention was to rescue her parents from the Outcasts.

Have Dragon Will Travel, Part 2
Astrid pulls Heather out of the clubhouse for some girl time. They head to another part of the island and are practicing their axe throwing. Heather shows Astrid her double sided axe, and Astrid wants Heather to show her how she made it. Heather tells Astrid she prefers close combat to throwing, and Astrid says it is not a bad tactic and then displays the element of surprise tactic, which Heather realizes. Astrid says that it is one of Hiccup's favorite Tactics. Heather then asks Astrid if she and Hiccup are a thing, which causes Astrid to throw her axe wildly. Astrid says they are just friends. But Heather doesn't buy it stating that she has seen the way Astrid and Hiccup are together. Astrid repeats that they are just friends. Heather says that Hiccup is cute, to which Astrid says, "I guess. If you like that unassuming, heroic, dragon rider type." Astrid then says Heather and Snotlout are a match made in Valhalla, but Heather says she is not into the macho viking type and that she likes smarts, like Fishlegs. Astrid is surprised at that and Heather says that she thinks he is funny and cute. Heather than says they have had enough boy talk and asks Astrid what else they do for fun around here. Astrid and Heather then run together and jump of the cliff and fall onto their own dragons for fun.

At the end, Heather is preparing to leave the Edge and go figure things out, and Astrid tries to convince her to stay, saying that she is here for her, but Heather does not change her mind and thanks Astrid for being her friend saying, "Astrid. It was nice having a friend again."

To Heather or Not to Heather
After Heather arrives at the Edge, she shares a hug with Astrid, having not seen her for months. Astrid and Heather then talk about why Heather didn't come back with them after the Viggo fiasco, and Astrid says she was worried about her. Heather than mentions that during her time with the hunters, they were playing a part and that she did not have time to think about Dagur being her brother. Astrid then tells her to not think about it, but Heather responds she has to and why she has to, with Astrid saying that if Heather was anything like Dagur they would have dropped her into a volcano a while ago. Heather then says they should talk about something less depressing, like Hiccup. Astrid says, "What about him?" Heather knowing that Astrid has feelings for Hiccup says, "Astrid, life is too short. You need to express your feelings. Stop wasting time. You two are perfect." Astrid replies that she could says the same about Heather with Fishlegs, adding that the two of them have practically worn out the flock of terrible terrors. Heathers responds saying that she has no idea what Astid is talking about.

Stryke Out
At the island where Hiccup is being held, Astrid and Heather fight the Dragon Hunters together, and Heather helps Astrid find and rescue Hiccup.

Shell Shocked, Part 1
Heather is able to figure out that Hiccup and Astrid are in relationship before the other riders are and is willing to give them time alone, walking away from them with a smile on her face, happy that Astrid has finally admitted her feelings to Hiccup.

Something Rotten on Berserker Island
After Astrid arrives on Berserker Island with the other riders, and is cleared through the checkpoint, she shares a hug with Heather.

Snotlout's Angels
Heather asks Ruffnut, Tuffnut, and Hiccup if Astrid and Snotlout will be long, as she wants to say goodbye to Astrid before she heads home to Berserker Island. After Astrid gets on Stormfly and heads back to her hut, Heather says that she'll just go and talk to Astrid herself.