Oooh! Thank you for asking this because I don’t think I’ve ever gotten to address it on tumblr before. I have lots on DA, so I’ll be referencing old conversations. First and foremost:
Hiccup Didn’t Need To Apologize.
Nobody freak out!
This is something I think a disturbing portion of the fandom never considered. Hiccup got too much blame for his interactions with Heather and Astrid got too much praise.
I don’t blame Hiccup for not trusting Astrid’s judgement. It wasn’t even that he didn’t trust her, he was just calling her out on her behavior—which was, if you look at it objectively (i.e. not with the knowledge we already have about Heather), marginally inappropriate towards Heather. She was rude, distrusting, and standoffish for no other reason than dislike.
Now, I’m fine with Astrid behaving that way, particularly if she’s usually hostile towards outsiders. Astrid has a weird beacon in her brain that lights up on the first whiff of any sort of deceit (remember the movie??).
What I’m not fine with is people calling Hiccup an idiot for choosing to defend Heather up until the point when her true intentions are revealed. In fact, anything else would have been out of character for him. He’s not stupidly trusting; he’s an empathetic young man who wanted to help a girl who was alone (something he could relate to); a girl was also enthusiastic about dragons, open to learning about dragons outside of trying to kill them, and also had some mechanical know-how.
Hiccup wasn’t even that interested in Heather outside of being genuinely friendly and wanting to help someone in need. And Heather had no romantic interests in anyone. Astrid’s jealousy, if it can even be called that, was fueled by the other teens’ teasing more than any suspicions regarding romance between Hiccup and Heather. She was annoyed Hiccup didn’t jump to take her side on something that she had nothing to back up other than an attitude.
Her “are you serious?” line in Hiccup’s room was out of line (something I realized watching the episode slowly to write the transcript). She felt victimized when she had no right to be—like the writers were trying to force our sympathy for Astrid right then and, unfortunately, it worked on some people.
So, Astrid totally jumped the gun in treating Heather like a criminal and because we, the audience, knew Heather was a spy, no one called foul on that.
It wasn’t until Astrid had hard proof of Heather’s lies that Hiccup believed her. All Astrid had to do was tell Hiccup what she saw and Hiccup was on her side.
I suggest trying to watch the Heather Report while knowing what only the characters know, and not what the audience knows. Hiccup was being overly optimistic, Astrid was being a brat.
Don’t get me wrong—I loved that episode for characterization. I thought Hiccup and Astrid were both more like their movie personas than most other episodes. I just didn’t like how the viewers were predisposed to dislike Heather and be on Astrid’s side before the episode even aired. We had weeks of false hype about a rival love interest to the point where most fans were all ready to support Astrid without even knowing the plot.
It’s actually rather interesting, because in the movie we were all on Team Hiccup without giving much thought to Astrid’s (or Vikings’) side of things. In the episode we were clearly herded towards giving Astrid sympathy without giving much thought to Hiccup.
Now, was Hiccup wrong for reserving harsh judgement towards Heather until he had some sort of proof that she was doing something bad? Wrong or right, it was at least Hiccup. Dangerously sympathetic. It might not have been smart, but it was definitely in line with his character. Just like it was in character for Astrid to get huffy and suspicious with no real proof other than hunches, and treat the victim of her suspicions with hostility.
But at the end of the day, Astrid didn’t really earn an apology. She earned the right to say ‘I told you so’ and that’s it.