I’ve been seeing a lot of posts saying that we weren’t given sufficient reason to accept that dragons and humans needed to part at the the end of the third film. But I personally felt that case was built up throughout the whole franchise, so I just wanted to offer my own two cents (this is obviously just my opinion). Yes, Hiccup has been somewhat successful at changing people’s minds about dragons, but for every single one of his gains, he’s met with a new enemy. After the first movie he does change Stoick’s and the people of Berk’s minds, but in Riders of Berk, he’s faced with Alvin and Mildew, who pose a threat to their new way of living. In Defenders of Berk, he does successfully change Alvin’s mind, but then he is met with Dagur’s refusal to allow for the peaceful coexistence with dragons. In Race to the Edge, he does end up changing Dagur’s mind, but then he encounters new threats to the harmony he’s trying to establish: the Dragon Hunters. He never is able to convince Ryker, and though he does eventually win Viggo over, he’s then faced with Krogan and Johann, who both die refusing to believe in Hiccup’s vision of human/dragon unity. In the second movie, though he once again manages to change Eret’s mind, Hiccup is dealt his most significant personal setback in his quest to make the world fit for peaceful human/dragon cohabitation. He actually loses his father over the course of trying to persuade Drago that humans and dragons can live together, which he ultimately fails to do anyway. But I think one of the most convincing arguments comes from Valka, who states that she has already tried to do the same thing that Hiccup is currently attempting, which ended the way it always will as long as evil exists in the world: war, and the destruction of her sanctuary. Even in the comic books, Hiccup is constantly faced with villains who oppose his vision of peace, and who constantly try to steal and manipulate Berk’s dragons, or harm both the people of Berk and the dragons. With every passing battle, Hiccup risks the lives of Toothless, the rest of the dragons, and the people he loves. Grimmel and the warlords are the final threat, setting fire to an extremely exposed and depleted Berk. As chief, Hiccup is now responsible for every life on Berk, both dragon and human. Though I agree Grimmel himself could have been presented in a more threatening manner, the fact remains that it’s beginning to be clear that this idea of peace is never going to be sustainable. Hiccup finally discovers a hidden refuge for dragons where they can be safe forever, and he realizes that if he does move Berk here, he risks ruining this last safe haven with the introduction of human greed. Who’s to say that future generations of Berkians wouldn’t decide to exploit and harm the dragons, or expand into the Hidden World and encroach on the dragon’s territory as the human population grew? And yet if the dragons stay with the Berkians, they’ll forever offer a target for hunters and conquerors, with dire consequences for both the humans and dragons. Hiccup’s act of sending the dragons away was the culmination of the never-ending adversity he’s faced throughout the entire series. Toothless’s arc with the Light Fury only drives home how vulnerable all of the dragons are if their Alpha has trouble balancing his ties with the dragon and human worlds. Because of his relationship with Hiccup and humans in general, Toothless himself has always been and will always be in peril, which has been proven throughout the series through the likes of Dagur and the Dragon Hunters. This becomes most evident during the final battle after he is captured. Toothless is faced with an impossible choice: either not put up a fight in order to save his new mate and in the process, allow all of his dragon subjects on Berk to be captured and/or killed by Grimmel and the warlords, or let the Light Fury die to save the rest of the dragons, who will probably be slaughtered or enslaved shortly anyway. Hiccup realizes these are the kinds of impossible choices Toothless should never have to make again in the future because of humans. The fact that Toothless nearly watched his new mate, all of his loyal dragon subjects on Berk, and his human best friend all die because of his friendship with that very human is the final straw for Hiccup. Toothless leaving had very little to do with choosing romance over friendship, as the Light Fury was only a catalyst to show Toothless how out of touch he has become with his dragon side. The dragons would constantly be in danger as long as their Alpha was in danger (as Valka’s Bewilderbeast proved), so both Hiccup and Toothless mutually agree that the dragons will be safest if hidden.
