Forest of Secrets is a children's fantasy novel, the third book in the original Warriors series, written by Cherith Baldry under the pen name of Erin Hunter. The plot is about Fireheart, a ThunderClan warrior, attempting to prevent his best friend Graystripe from falling in love with Silverstream, whom Graystripe is not allowed to fall in love with. Silverstream later dies giving birth to Graystripe's kits. When RiverClan claims the kits, Graystripe makes the difficult decision to join RiverClan. Fireheart also becomes deputy after Tigerclaw, the deputy, attempts to kill the leader, Bluestar. The main theme of the book is forbidden love. Forest of Secrets takes place in a fictional forest based on many natural locations.

Fire and Ice is a children's fantasy novel, the second book in the Warriors series, written by Kate Cary under the pen name of Erin Hunter. The plot centers around Fireheart and Graystripe, newly promoted warriors of ThunderClan, which is one of the four groups of feral cats living in the wilderness. Fireheart learns that his best friend Graystripe has fallen in love with Silverstream, a warrior from RiverClan, even though it is against the cats' "warrior code".