In Ragnarok: the End of the Gods, Byatt recounts how she became fascinated with Norse mythology as a little girl. In Ragnarok, she refers to herself as 'the thin child', a World War II evacuee to the British countryside. The thin child discovers a book titled Asgard and the Gods written by a German Dr W. Wagner. Since this is wartime, the child is curious about this book written by a German who've she's only heard as being people to be feared. She becomes fascinated by the world and the gods in the book. She tries to compare them to the Christian God and the stories in the Bible. She comes to prefer the world in the book and the how their world ends.
I can see why Byatt was interested in these stories during this time. It must have seemed as if the world was ending. Perhaps these stories helped her make some sense of it all. There isn't a story here other than a child reading a book and the memories of the woman who was that child. The myths are told in a straight forward fashion. She says in the afterword that the gods don't have personalities only attributes, so don't expect great characterization. It's Byatt's style that's the money here.
I rarely wish for forewords but in this case I wish the afterword had been the foreword. I would have appreciated what she was trying to accomplish more than I did while reading it. In the end, as I read the afterword I thought, "Oh, okay that makes sense to me now." The stories of the gods are sometimes weird and make little sense. Why do they do what they do? Who knows. Mostly because they can. I enjoyed reading about this strange world, though I was less enamored with the giant sea serpent Jörmungandr than Byatt is. That was a long couple of chapters. (She ate fish, then she ate some more fish and got really big.)
Ragnarok is a strange but interesting little book, beautifully written. I feel that I could read it again and get more out of it the second time round. This is part of the Canongate series on mythology retold by celebrated authors.