Eric is an obnoxious thirteen-year-old Demonalogist Hacker in the novel
Faust Eric who gives his address as 13 Midden Lane, Pseudopolis, the Discworld, On Top of Great A'Tuin, The Universe, Space, nr. More Space,. Eric inherited most of his demonology books and paraphernalia (as well as a talking parrot) from his grandfather; his parents, apparently convinced that their son was destined to become a gifted demonologist, allowed him free rein over his grandfather's workshop. Eric was relatively unsuccessful as a demonologist until he attempts to summon a demon to grant him the standard three wishes: to rule a kingdom, get a girl and live forever. Easy enough for the average demon. Instead, he managed to summon Rincewind from the Dungeon Dimensions. Rincewind, while he may be summoned and suffer all the potential maladies that come with being a demon (a proverbial chain, a circle that burns him, etc), is not a demon but a failed wizard. He can't actually snap his fingers and make wishes come true at will, or if he does, something goes badly wrong (much like the usual granting of wishes in fairy tales). However, the rather more powerful and malevolent Duke Vassenego, one of the supreme demon lords of Hell can and is the real player behind the scenes. He has his reasons for doing all of this, chief amongst which is his plotting to supersede Astfgl as the ruler of Hell. Together Eric, Rincewind, a Parrot who's mastered the word 'wossname', and Rincewind's Luggage travel around Discworld's past, present and underworld dimensions. Along the way, they journey across Time to such diverse locations as the Discworld rainforests, the Tsortean War- the Discworld version of the Trojan War-, and the beginning of the universe (during which he became somewhat more likeable), experience Eric's three wishes. Eric is last seen escaping from Hell with Rincewind, and it is unknown what happened to him afterwards. He is presumably still alive as Duke Vassenego let them go in order to a) encourage humanity to continue to stupidly dabble in demonology and b) to really annoy Astfgl.
Eric might be a spoof of Michael Moorcock's fantasy creation, the necromancer Elric, who is a necromancer/warrior in Moorcock's series of straight, if high-camp, fantasy novels. Elric is handicapped by his being a weak and enfeebled albino, whose energy fails rapidly if not sustained by eldritch drugs or the proximity of the dread hell-sword Stormbringer. (Kring in the Discworld-view) He regularly calls for the support and patronage of the Chaos demon/god Arioch to assist him. Arioch sometimes obliges. Elric is the first manifestation of the Eternal Champion, doomed to be continually reincarnated down the echoing corridors of time and space to serve whichever threatened civilization requires his services.