Guy and Eep first met when Eep saw the light from Guy's fire from the safety of her cave. She finds his campsite, and Guy (dressed in a boar-pelt) watched from behind her in awe. Eep gets the first-hand on him and nearly breaks his back. The two bond for a shortwhile and warns her of "The End", a cataclysmic event that would destroy the world they are familiar with, and that he is following the sun to a paradise he named "Tomorrow". He gives her a shell, and that if she needed him, she could blow into at to "call (him)".
After "The End" destroys the Crood's cave, Eep finds a broken horn (since her family destroyed the shell) and Guy saves the family from a flock of Pirahna-Birds with a torch. From then on, the Croods hold him prisoner in a log, thinking his skills would be useful. Through their adventure, Eep holds a crush on Guy, with Guy holding a mild fondness with Eep that slowly grows.