Back from Sundermount is an Act 2 companion quest for Merrill in Dragon Age II.
Acquisition[]
The quest is obtained regardless of choices made in Mirror Image. Travel to Merrill's Home at the Kirkwall Alienage in Lowtown and speak with her.
Note: The player may already have acquired Merrill's Questioning Beliefs at this stage, but if this is the case, this quest will trigger first.
Walkthrough[]
If Hawke awards Merrill the Arulin'Holm, she appreciates the assistance. She comments that even her own kind do not value her efforts.
If Hawke kept the Arulin'Holm, she berates Hawke for breaking their promise and hampering her efforts, stating that she is fulfilling her duty to her people.
Result[]
If you gave Merrill the arulin'holm, you net 
Merrill: friendship (+5) for the Diplomatic choice.
If you denied Merrill the arulin'holm, you net 
Merrill: rivalry (+10) for the Aggressive choice and Merrill: rivalry (+25) for either of the Sarcastic or Diplomatic choices.
If Hawke gave her the arulin'holm, they also have the opportunity to flirt with Merrill here, and if her friendship or rivalry is high enough, she will meet Hawke after the quest at the Hawke Estate at the end of the following quest. Note that this flirt is not required by any means, as any will be sufficient to send her to Hawke's estate, including the Flirt option available in the next quest.