Gathering Storms

Gathering Storms is a main quest in the Fallout: New Vegas add-on, Honest Hearts.

Quick walkthrough

 * 1) Talk to Daniel near the Sorrows Camp.
 * 2) Tell Daniel whether the Sorrows should fight or flee.
 * 3) Your decision will either begin Flight from Zion or Crush the White Legs.

Detailed walkthrough
The quest is given upon completion of The Grand Staircase, The Advance Scouts, The Treacherous Road and River Monsters. When the Courier speaks to Daniel, he will give the Courier the option of either:
 * Helping the Sorrows evacuate Zion Canyon, beginning the quest Flight from Zion.
 * Fighting the White Legs with Joshua Graham, beginning the quest Crush the White Legs.

Telling Daniel which option the player has chosen completes the quest.