An ancient magical compact between elves and humans binds elves in serve to wizards, as well as appointing elves "to stand between the world of wizards, and the Lands Below." The compact further stipulates that elves must ferry humans from the Lands Above to the Lands Below if presented with an obol.
In May 2009, Alexandra Quick invoked the compact by summoning the elf Em and giving her an obol in order to secure passage through the gateway below the Charmbridge Academy.
In November 2010, Quick learned from Bran and Poe that elves cannot be forced against their wills "to hunt for Dark Wizards" because doing so "is not part of the Compact" and "not part of the Compact."