Beasts of Olympus 7: Gods of the North by Lucy Coats
Seventh book in the fun and funny Greek mythology BEASTS OF OLYMPUS series. The Greek gods and goddesses meet the Norse gods in this beastly mythical mash-up. Demon must travel to Asgard, to help save Odin's boar, Goldbristle - without his shining light, nothing can grow and all of Asgard will wither and die. But nothing Demon does has any effect, and Asgard is a strange place - he must contend with Fafnir the ice dragon, ravenous and dangerous Fenrir the wolf and, worst of all, the treacherous trickster god Loki, who is determined to cause mischief. With the help of Ratatosk, a giant squirrel, and Thrud, the daughter of Thor, Demon tries his best to fulfil his quest before Odin decides to freeze him into an icicle and use him for spear practice...