In the books, Spitelout's real name is Baggybum the Beerbelly and is the younger brother of Stoick the Vast. Snotlout is thus Hiccup's cousin and would have been future leader of Berk if Stoick were not the tribe leader, which is why Spitelout and Snotlout are constantly trying to prove they are above the rules and would make better leaders.
This episode introduces the Singe Tail dragon.