Acquisition
Seeing a poster concerning a reward for the rescue of the viscount's son who has gone missing is the first clue. This can be found in high town in the market area. Another source also claims that overhearing a heated conversation between Seneschal Bran and Ginnis, the leader of a band of mercenaries, the Winters. Either way, talk to the Seneschal to get all the detail concerning the quest. Accepting will get you 
Aveline: friendship (+5) and Carver: friendship (+5). If you refuse, you get 
Aveline: rivalry (+5) and Carver: rivalry (+5), but the quest stays in your journal and can still be completed. Isabela, Anders, Varric and Fenris have no reaction.
Walkthrough
There are two choices when arriving at the Wounded coast, taking the north road or the southern one. The North road is the scene of a small fight where two dwarf guards are defending their boss who then once things calms down offers the player the quest Blackpowder Promise. This can be received in a random encounter as one travels to the Coast. On the southern road the player may encounter a Dalish Elf accusing a man of having murdered her mother while he was a werewolf. If the curse was lifted, the man was indeed guilty but felt ashamed of his actions. If the Warden had sided with Zathrian, the man is an innocent bystander, wrongly accused. Hawke can intervene to convince the elf to spare his life, or state that it is none of his/her affair. If the dialogue choice is made that convinces the elf to spare his life by speaking about what her mother would want (available to a friendly Hawke), it will net Isabela: rivalry (+5). If he was never a werewolf, choosing to save him will net Isabela: rivalry (+5), and leaving him will net Isabela: friendship (+5)
Some further walking and the choice to take a road going straight south is given, take it and a scene should be played out when one reaches the Winter mercenary band along with the Viscount's Son in a somewhat heated arguement concerning rewards and a murdered Qunari friend. Ginnis will insinuate that Saemus was in a sexual relationship with the qunari. This situation quickly turns more heated as the mercenary bands turns on the player when they arrive, with the Winter leader threatening to cut out Saemus' tongue for berating her over having killed the qunari. Several waves of mercenaries will show up. Once the mercenary is dead, ready your party and you, along with the boy, will travel back to the Viscount's Keep.
At the Keep, the Viscount and Saemus will start arguing about the treatment of the qunari. Saemus believes that they ought to be respected, while the Viscount sees them, or rather their influence, as dangerous. Here, Hawke can either excuse him/herself by saying that this is “not my affair”, which leads to the reward, the party leaving the Viscount's office and the quest ending. Hawke can also side with the Viscount or Saemus (or call both of them idiots). Either way, the quest will end, leaving the "happy" family to argue the finer points of Qunari, running away, and mercenary hirelings.
Result
The Viscount's son, Saemus, is rescued.
When speaking with the Viscount, Saemus begins to argue with his father about the "abduction". You have the option to give your opinion. Your choices will have the following results:
"This is clearly not my affair."
Aveline: friendship (+5)- Isabela: friendship (+5)
"Yes, your son went too far."
- Aveline: rivalry (+5)
- Carver: rivalry (+5)
"You're both stubborn fools."
- Aveline: friendship (+5)
- Carver: rivalry (+5)
"Saemus is right to question."
- Aveline: rivalry (+5)
- Carver: friendship (+5)
(Anders, Merrill, Fenris and Varric are not affected by any conversation choice.)
Later, in Act II, Seamus makes reference to your dialogue choice when conversing with him in the Keep. If Hawke chose the neutral "not my affair" option, Seamus will state Hawke was able to make a difference in the situation even by taking a neutral stance, and that, due to Hawke's actions, some of his anger against the world has decreased. A similar conversation occurs if you support Seamus against his father, because he does not feel he is alone in his beliefs.
Rewards
5 