Eddie makes his debut in The Drawing of the Three, in which Roland encounters three doors that open into New York City of our world in different times. Through these doors, Roland draws companions who will join him on his quest, as the Man In Black foretold. The first to be drawn is Eddie Dean, a drug addict and a first-time cocaine transporter. Eddie lived with his older brother and fellow junkie Henry, whom Eddie revered despite the corrupting influence Henry had upon his life. Roland helps Eddie fight off a gang of mobsters for whom he was transporting the cocaine, but not before Eddie discovers that Henry has died from an overdose of heroin in the company of the aforementioned mobsters (after which the mobsters decide to chop off Henry's head). It is because of Eddie's heroin addiction that he is termed 'The Prisoner', and that is what is written upon the door from which Roland draws him.

Roland also acquires medicine for his infection during the trip to Eddie's world, but this only temporarily quells the fever.

Eddie passes through the door into Roland's world, and faces the typically horrible withdrawal symptoms, but also shows an affinity for the ways of the gunslinger. Unwillingly at first, and somewhat forcibly, Eddie becomes Roland's companion through Mid-World, and soon falls in love with (and marries, in a way) Susannah, the next member of Roland's ka-tet.

During the attack on Algul Siento during the final novel, Eddie is killed by Pimli Prentiss, the master of the Breakers, via a shot to the head. Susannah is quite obviously distraught by this event, and eventually has Patrick Danville draw her a door to another world. Susannah crosses over into a world where an Eddie who strongly resembles "her" Eddie is alive and well and living in New York, along with his brother Jake (both now named Toren).

Roland also notes that Eddie's character strongly resembles that of Cuthbert's, a gunslinger of Roland's past, and one of Roland's greatest friends. The character of Cuthbert is mentioned in Browning's poem and is described most fully in Wizard and Glass, although he is first mentioned in The Gunslinger.