Sea of Trolls by Nancy Farmer Jack is a poor Saxon farm boy when the Bard chooses him to be his apprentice. He's learning to pay close attention to everything and feel the Life Force. Then the Bard senses ships coming. A lone monk stumbles into the village from the Holy Isle, raving that berserkers destroyed the whole island, burning the books and killing the monks and nuns. This is the pebble in the pond. The villagers all hide, except for Jack's little sister, Lucy. She is convinced that she is really a princess, and that the raiders are knights come to take her to the king and queen. Jack follows – and both of them are captives on the Northmen's raiding ship. They are being taken back to the kingdom of Ivar the Boneless, whose half-troll wife, Frith, has been trying to kill the Bard. Lucy is intended as a gift for Frith, and Frith intends to sacrifice her to the goddess Freya. The only way for Jack to save her is to journey to Jotunheim, the Kingdom of Trolls. The great Olaf One-Brow and the ornery young shield maiden Thorgill, as well as a crow who found their ship in the middle of the ocean, come to help Jack on his quest.
Once again, Nancy Farmer delivers with a tale of adventure stirring enough to keep indifferent readers hooked which nonetheless has deep levels of meaning. Jack learns to respect his captors, even as he is horrified at their violence, the pride they take in going berserk and their hope to die in battle. He was raised a Christian, yet trained as a Bard to do magic, and meets the deities of other religions over the course of his quest. Over and over again, Jack sees the beauty in all life – even life he's been taught to fear – and still knows that they must remain enemies. The book is also set firmly in period just following the historical destruction of the Island of Lindisfarne, and the fantasy elements are all drawn directly from the myths of the period. As a stranger, Jack is good at noticing the Northmen's ways, making it a good introduction to the period for anyone. It may not be straight history as we'd see it now, but it's certainly a tale that people from the time would have felt as true, which is even better.