In the Quest for Glory series, the Hero encounters Erasmus and his rat familiar Fenrus several times throughout the course of his adventures. Erasmus is first met in Spielburg in the original game. He lives high atop a mountain in a home guarded by a gargoyle, who poses the Hero several questions before he can enter. Erasmus helps the Hero on his quest to save Spielburg from bandits, evil wizardy, and even may help the Hero learn new spells, if he has the proper training.
In Quest for Glory II: Trial by Fire, Erasmus sponsors the Hero if he is a mage to enter into the Wizard's Institute of Technocery, letting him become a fully wizard.
In Quest for Glory IV: Shadows of Darkness, Erasmus and Fenrus can be heard trying to summon the Hero to Silmaria throughout , but due to the interference of Katrina's dark magics remain unable to do so until the end of the game, when he is finally transported to the setting of the fifth game.
In Quest for Glory V: Dragon Fire, Erasmus and Fenrus are part of another magical institution in Silmaria, and sponsors the Hero for the Rites of Rulership that the game revolves around.