User blog comment:SayuriDarling/Magnus Chase and the Gods of Asgard Official Discussion/@comment-25044056-20141104003750

Valkyries: battle maidens, they went out to the battlefield and chose the bravest warriors to fight for Asgard, they also served drinks at Valhalla mead hall and traditionally were the lovers of heroes in Norse myth.

I believe when Magnus Chase enters the world of Norse mythology he will have a Valkyrie assigned to him, as a guide. This character will serve a role similar to Annabeth, starting out as an expositional character then maybe changing to a love interest later on. Perhaps this perticular Valkyrie has never left Asgard and Magnus has to lead her through the mortal world just as she leads him through the mythological world.

Einherjar: mortal warriors who after dying were chosen by the Valkyries to fight for Asgard.

I think that Magnus Chase in the first book will have a mortal friend who he has to keep his involvement in the mythological world a secret from, then at the end of the book or in the second book this friend dies and is chosen by the Valkyries to fight for Asgard.

Loki, the Norse god of mischief and chaos. He was born a Jotun but became one of the Aesir when he mixed his blood with Odin's and they drank it together. Loki is usually portrayed as an amoral trickster. The only stories where he is shown as an antagonist take place after his children (the Midgard serpent, Fefnir the wolf, and Hel goddess of death) were imprisoned by Odin

I predict that in each one of the three books, Magnus will fight one of Loki's children.

Odin. A morally ambiguous king, even more so than Zeus. while Zeus and his brothers defeated Kronos to avenge the crime of eating his children alive, Odin killed Ymir the first Giant for apparently no better reason than he needed his corpse as raw materials to build the world out of. This is probably what started the eternal war between the gods and the Jotuns. He also imprisoned Loki's 3 children for crimes they had not yet commited, it's possible that Loki killed Baldur to avenge the imprisonment of his children.

I predict that Magnus Chase will either be the son of Loki or the son of Odin. Odin was the progenetor of the Volsung family, a dynasty of Norse demigod heroes.