Tantrum O'Ugerly Hotshot, nee Hotshot is the daughter of UG, Chief of the Uglithugs, and wife of Humongously Hotshot. She has had thirteen fiancés but they are all captured by the chief Berserk and chained up to be later fed to the beast of Berserk (the dragon Furious). No fiancé is actually fed to the beast. She is tone-deaf. Fishlegs wrote her a love poem. When the Hooligans, who were looking for Camicazi, landed on the Uglithugs beach, UG told them that a Hooligan had been writing his daughter love letters, which was strictly forbidden for people who were not of royal blood. Knowing it was Fishlegs, Hiccup lied to UG, saying it was him.
So far, this is the only book she appears in. Princess Tantrum is the love interest of Fishlegs and after he met her he sent her poetry. However when Ug found the poetry he threatened to kill every unmarried Hooligan unless Fishlegs owned up. Hiccup owns up for him as Fishlegs is not of royal blood so he would be killed.
However, it is revealed that Tantrum actually loves Humongously Hotshot the Hero. When Hiccup releases the fiancés from the berserk island they all creep back into the castle to steal Princess Tantrum among other things. Princess Tantrum is now married to Humongous and they have sailed away together in his boat.
Tantrum is shown to be somewhat spoiled, hence her name. She also disliked the luxuries she enjoyed when she was princess of the Uglithug Tribe. Rather than stay in the comfort and protection of her tribe, Tantrum yearns to explore the world and "live by the sword".
Tantrum is shown to have wanted to marry Humungously Hotshot the Hero and goes off singing (out of tune) with him into the sunset on a boat together.