The Hag of the Iron Well was created by Bronwyn Taggart and penciler Ryan Kelly in The Books of Magic issue 57 in 1998.
Major Story Arcs
The Hag lives by a magic scrying pool that sometimes looks like a pond and sometimes like a well (the well is ringed by stone, so it is unclear why it is called the Iron Well). She is immortal and seems to live outside the normal timeline, even for a fairy. She has seen all of Faerie be rebooted multiple times.
At some point she has an affair with King Magnus and they have a son, Amadan. He seems destined to be good, but because Magnus did not acknowledge him as his son, he turns to evil and manipulation.
Sturm and his brothers visit the well one by one, and she asks each of them to save her silver treasure, by which she is referring to a silver snake. The first two fail and die. Sturm arrives, and she gives him a magic armband, which allows him to walk underwater. He finds the snake and wrestles it to the surface. She is happy, and resurrects his brothers as a reward. She predicts that he will one day save all of Faerie with the magic armband.
She and the Gyvv, a very powerful creature, sit by the pool at the end of one cycle of Faerie and look back at what happened this cycle, and discuss past and future ones. Then she adds a tear to the well, casting the spell that starts it anew.
Note: she is not named in the comics in which she actually appears; she is named in The Books of Faerie: Auberon’s Tale #1, in which she does not appear.