Lost Dues in Good Faith

 is a side quest in.

Synopsis
Kahn asks you to help her find Oswald, an old elf who owes her 5,000 coppers. Oswald favored Aenalys, one of the courtesans on the second level of The Wild Mare.

Overview

 * 1) Talk to Kahn in The Wild Mare.
 * 2) Find Oswald's whereabouts by obtaining his journal, either by stealing it from Aenalys' armoire, or by convincing her to give it to you, returning to Kahn once you have it.
 * 3) Travel to Oathbinder's Sanctum and either rescue Oswald from the cultists, or let him die.
 * 4) Return to Kahn and tell her what happened, or lie and give her money

Walkthrough
This quest can be started by either coming across Oathbinder's Sanctum during your travels (see below), or by talking with Kahn in The Wild Mare.
 * Talk to Kahn to get the rundown of the quest. Oswald owes her, and she's offering 20% if you can find him and return the money. You can push her a bit in order to bump it up to 40% (no check required), and with Diplomacy 5 up to 60%, and then with the Merchant background up to 80%.
 * Kahn tells you that Oswald was especially fond of Aenalys, one of the courtesans upstairs. Head upstairs and talk to find out more. She will deny knowing him and try to kick him out. You can use Diplomacy 4, Streetwise 3, or Insight 4 to make her spill the beans (or pay ). She will explain that Oswald was quite sentimental and visited her to listen to old epics in Eld Aedyran. However, he started behaving like a paranoiac in recent days and eventually gave her his journal for safekeeping, then disappeared. She will direct you to her armoire.
 * Otherwise, you need to break into her armoire and pilfer it for himself, then return to Kahn to read through it. She will wonder where they've taken. You can prod her memory with Survival 4 or a Deadfire origin. She will eventually mention a weird old temple in the Karatapu Channel to the southwest of Neketaka. Head to the Oathbinder's Sanctum by ship.

Finding Oswald
 * Make your way through the sanctum. On the fourth floor you will come across a group of Woedican cultists led by Inquisitor Lödwyn. They accuse Oswald of oath breaking, and sentence him to death. You can choose to fight and save Oswald, watch him die from the shadows, convince them to let him go, or side with them and allow him to die.
 * If you discovered the soul of a murdered innocent on the second floor, you can either side with the cultists, or talk them down by convincing them they have wronged many souls.
 * If you're honest with them and say that they killed only one innocent, you can then let them carry on with their judgement. They will reward you with for your good faith, though you lose relationship with Aloth and Serafen. This completes the quest, and you will be escorted back to the entrance.
 * If you lie and say that they wrongly killed "A handful". Passing a hidden Bluff 3 check will cause her to question you (looping back to the previous dialogue options), and failing will cause her to attack immediately.
 * You can talk them down by lying, saying they killed "Too many to count". This requires a hidden Bluff 7 check to succeed, otherwise they will attack immediately. Accepting what you have said, Lödwyn agrees to let Oswald go, and the cultists escort you both back to the first floor of the dungeon.
 * If you step in and save Oswald (either by talking them down, or killing the cultists), and have 6 Diplomacy or 5 Intimidate, he will give you a unique ring, Drunkard's Regret that saves you from hangovers if you drink while wearing it. He will also offer to join your crew. Oswald will also come clean, and tells you that he's broke and can't afford to pay Kahn back.
 * If you let him die (either by hanging back and letting the judgement carry out, or killing the lot of them, NOT by siding with the cultists, as they will escort you out) you can loot the ring from his body, and discover that he doesn't actually have the money after all.
 * Note that if you started the quest via entering the sanctum (and not via Kahn), deciding Oswalds fate will complete the quest.
 * Either way, you can head back to the Wild Mare and talk to Kahn to wrap things up.
 * If you let him die, you can tell her that he was executed. She will shed a tear for Oswald, but will accept the fact and leave.
 * If you let him live or die, Kahn will be nonplussed about the whole affair, all she cares about is the 5000 coppers. You can lie to her and give her the "cut" (between and, depending on your prior arrangement) and she'll leave happy. Otherwise you can be honest and tell her than Oswald was flat broke. She'll be annoyed, deeply, and storm off, leaving the Archipelago.

Alternative route
If you went to Oathbinder's Sanctum prior to talking with Kahn, the quest will complete once the fate of Oswald is decided. Upon returning to Kahn (assuming you do) the following interaction will occur:
 * You're able to tell her that you met him not long ago, in a humongous pyramid dedicated to Woedica, or lie to her and say that he's elsewhere
 * If you let Oswald die - You can tell her the truth, and say that he died, or lie to her and say that he's totally fine and went his own way.
 * If you let Oswald live, and either didn't add him to your crew (or he isn't on your current active crew) - You can tell her that you saved him, but left him to his own devices.
 * Either way, she doesn't care for the details, and asks if he had any coin on him.
 * You can tell the truth again and say that he was broke. She thanks you for the information, accepts the fact, and leaves.
 * Or you can lie to her, and say that Oswald was loaded, and that his riches belong to you now. She'll ask you to hand over the coin (see below).
 * If you let Oswald live, and he is currently part of your active crew, Kahn opens by asking if you're the captain with the "ancient Aedyran elf on your crew", claiming that he owes her money and that it's your responsibility as his captain to pay his debts.
 * The debt is, though with Diplomacy 6 you can negotiate it down to half the amount.
 * If you pay her, she takes the money, and tells you that she's sorry that Oswald dragged you into this, though she's glad that you've given him honest work.
 * Otherwise, you can tell her that Oswald is nothing but a broke old drunk. As above, she will storm off angrily.
 * With Intimidate 8, you can express your badassery for just having waded through an ancient pyramid filled with monsters and cultists. This will shut her up, and she will quickly down her drink and leave.


 * Interestingly, you can re-trigger the start of the quest again by saying "Why do you care?", or lying about Oswalds whereabouts upon first talking to Kahn. While this doesn't un-complete the quest, it essentially makes the quest act as if you had already talked to Kahn before finding Oswald, thereby opening up the "returning" dialogue tree as per the Kahn quest route.
 * You gain no XP for any of this, as the quest will already be finished.