Snotlout

Snotlout is Hiccup's cousin that happens to be good at everything; swordfighting for one. His dragon's name is Fireworm, a Montrous Nightmare often seen jabbing at Hiccup's dragon, Toothless, much like Snotlout to Hiccup. Snotlout's "sidekick" seems to be Dogsbreath the Duhbrain, who almost kills Hiccup because Snotlout took off the cover to Dogsbreath's sword.

Snotlout also found the decoy of the treasure of Grimsbeard the Ghastly in the second book.