Fairbanks' Trust is a side quest in Dragon Age: Inquisition
A woodsman known as Fairbanks has come to the Inquisition, offering what he calls "information of value" in exchange for aid in fighting the Freemen of the Dales, a band of rebels in the Emerald Graves.
Obtained upon reaching Skyhold at the end of the main quest In Your Heart Shall Burn. It serves as an introduction to a new area to explore: Emerald Graves.
Complete the war table operation, Make Contact in the Emerald Graves, which costs 8 Power to complete the quest and unlock the new area.