Roger Zelazny's Chaos and Amber (Dawn of Amber Trilogy Book 2)

In CHAOS AND AMBER, Dworkin and his son Oberon arrive at the Courts of Chaos to discover, and confront, their hidden enemies. But things don't go as planned. Oberon has a terrible physical reaction to being in Chaos, while assassination attempts are made on both his and Dworkin's lives-and the traitor in their family remains a hidden but quite real threat. Dworkin takes Oberon on a desperate journey, pressing deeper into Shadow than ever before. Here, Oberon discovers more of the true nature of his father...and of his real mother. But they have been followed, and a horde of hell-creatures attacks. Ultimately, Dworkin must create a new Pattern with his own blood to save himself, his family, and the future.