Percy Jackson, Httyd, rise of the guardians crossover

Takes place during lost hero

Hiccup and Jack are demigods that where

Hiccup must be the son of hecate, goddess of magic, witchcraft, Necromancy, prophecy, and dragons/ and legacy of Hephaestus

Jack is child of Boreas, God of the North wind, Lord of winter, legacy of Khione

They are with the group while on the bus,

Jack and hiccup are in a polyamorous relationship with Leo

Hiccup has a pet cat called toothless, that can become a black dragon

Hiccup powers include the ability to communicate with all animals (hecate animal is all wild animals), Mystiokinesis, and his is great in the forge

Jack powers are, ice, frost, and wind manipulation, and idea creature creation

Prophecy of seven now became prophecy of 9, add hiccup and Jack to prophecy
The new prophecy is

Nine half-bloods shall answer the call,

To storm, magic, winter, or fire the world must fall.

An oath to keep with a final breath,

And foes bear arms to the Doors of Death.

Pairing is hiccup x Jack x leo