Hold up Is snotlout hiccup's cousin
Long Answer: In the book series, Snotlout is explicitly stated to be Hiccup’s cousin. His relation to Hiccup is in fact a major driving factor in the book series. You can see the family tree here and read that Snotlout is the son of Stoick’s younger brother Baggybum the Beerbelly.
Where it gets complicated is that the entire fandom debates upon whether or not Snotlout canonically is Hiccup’s cousin in the DreamWorks franchise. The DreamWorks franchise does diverge from the plotline of the books in some areas, after all, including some of the details of Snotlout’s family life.
I personally regard Snotlout and Hiccup as cousins in the entire franchise for both the book series and the DreamWorks franchise. Snotlout’s character in the movies does diverge somewhat personality-wise and background-wise from what he is in the books; he is younger than Hiccup in the franchise, whereas in the books he is three years older. He acts differently and makes different choices. However, his design and intent is much the same, and we can see that embedded within the first movie. I think that where we have no answers from the movies and no contradictory evidence otherwise, we can use the books to assume some more information about him. Unless the movies contradict the books, I say we should call canon canon wherever it comes from.
Now where the debate comes in is from the information we know about Snotlout’s father. Snotlout’s father is named “Spitelout” in the movies, not “Baggybum,” though if you read up on the making of the first movie, Spitelout’s role was once going to be much more closely related to how Baggybum acts in the books. So those two characters are conceptually related, and Snotlout still is related pretty decently to how he is in the books.
But the problem is that Snotlout’s dad is Spitelout Jorgensen, part of the Jorgensen clan, according to the DreamWorks franchise. Not the Haddock clan, where Hiccup and Stoick are from. Consequently there is some complications explaining why Snotlout and Hiccup have different last names and apparently different clans according to “Thawfest.” Still, there are a number of viable theories out there that combine book canon with DreamWorks movie canon, and I think all of that is a fair point to argue. Spitelout being Stoick’s half-brother is a common argument held. As I see it, unless we are explicitly told otherwise, we should assume that Snotlout’s familial relationship in the movies is the same as it is in the books.
I also just think that the relationship between Hiccup and Snotlout screams “relatives.” They totally act like it. They bicker like they’ve known one another forever and have had to suffer being in close contact for a while. These kids have had to suffer being in holiday gatherings and many other family events.
Some people may disagree with me on the DreamWorks perspective, and that’s okay. I’m not going to argue it. I just say go with overarching canon. Snotlout is Hiccup’s cousin in the book. Snotlout’s character in the movies is based off the boy in the books. There is no contradiction in information about Snotlout’s relation to Hiccup in the movies and films. Snotlout is best assumed to be Hiccup’s cousin in the movies.
So the short answer is “Yes, they’re cousins.” The long answer is, “The books make it obviously true; DreamWorks makes it complicated.”
