This book is the reason I can never quite believe that Loki is evil.
See, it was my very first introduction to Norse mythology. I'd long adored D'Aulaires' Book of Greek Myths, but had not yet encountered its northern counterpart. (I think the edition of this novel I read back then had an afterword explaining who the gods were, or all the reveals at the end would have flown totally over my head.) Thanks to Diana Wynne Jones, I'm subconsciously convinced Loki's a sweetie who never really meant to hurt anybody.
It's also the last of my top tier of favorites, which means I did a book recommendation for it yonks ago; read that for a plot summary.
This was her fourth book published (third fantasy), and as fjm said in the comments to Witch's Business, it's the first one to really feel like a DWJ novel. Not just because of the neglected kid protagonist, but because the fantasy isn't random; it's a meaningful layer to the story, and not entirely shiny. Luke may not be a villain, but he isn't quite what you'd call good, either. He's far too pleased with his own cleverness and power, and not inclined to think about the cost to others unless somebody reminds him.
I'm thinking particularly of the fire while David's out shopping with Astrid, and the quiet, intense way that Luke goes about it. There's a sinister edge to the scene that strikes me as very DWJ; it's there but not in your face, which is a balance she was very good at striking.
With the knowledge of Norse mythology I have now, though, I do have to wonder a bit at her characterization of Loki. Luke claims the death of Baldr was supposed to be a fun trick, that he didn't know it would kill the guy. Okay . . . but what about the bit where Loki masqueraded as Thokk and refused to weep for Baldr? Was that a fun trick, too? And he claims he gave himself up to be imprisoned, which I'm willing to accept on the partisan grounds that they never would have caught him if he hadn't let them -- but that isn't exactly the way the myth goes.
On this re-read -- with a semester of Old Norse, a thesis on Viking weapons, and about fifteen sagas under my belt, not to mention both Eddas -- I noticed a lot of things that had never really registered on me before. Place-names: not just Wednesday Hill and Thunderly Hill, but Ashbury (Yggdrasil is an ash-tree) and Lockend (the actual location of the house, and Luke talks about David having "unlocked" his prison). The Rainbow pub outside the ordinary Wallsey, and the rainbow light along the bridge at the other Wallsey. The cameo appearance by Nidhogg. My mental image of this Thor still owes too much to the Mr. Lynn type, though; he's described as tall, but there's nothing about his build, so I see him as way too lanky for who he's supposed to be. I also find myself frowning a little at Chew now, who isn't remotely like the conception of Tyr I've formed in the interim. (And why exactly does Mrs. Fry have it in so vehemently for Luke? Is it because of how he trash-talked her in the Lokasenna? He trash-talked everybody then. More likely it's because of Baldr's death, even though the pairing of the Frys suggests she's Freyja more than Frigg.)
I do love the valkyrie chauffeurs, though. And Sigurd and Brynhild -- I think of them by their Norse names, now, even though the book leans toward the Germanic. They really stuck with me, even when I didn't know their story; one of my unpublished novels (a Viking revenge epic) has a scene in it which owes a fairly direct debt to the image of Brynhild sleeping in the fire. The notion that she would want to give the finger to Odin and all his kin is pretty plausible, I'd say, after what happened to her.
As usual, comments are welcome on previous posts, and feel free to request books you'd rather hear me talk about sooner rather than later. (The Merlin Conspiracy is up next for that reason.)