Thieves' Guild Stronghold

Remember to loot Mae'Var's place clean and do not store any important items in there before reporting back to Renal for rewards, for you have no means to return to original Mae'Var's Guildhall after accepting it as your stronghold. Single, multi, or active thief of dual-class protagonists are eligible for thief’s guild if and only if they have no other strongholds after completing Find Proof of Mae'Var's Treachery, which means accepting Renal Bloodscalp‘s offer will lock away any other strongholds options if available.

Assigning fellow thieves
Go to Mae'Var's Guildhall, you now have a new guard outside, Brannel, whom you can chastise if you feel like it. Enter the hall then open the top door to talk to Jariel.

Jariel explains the workings of your guild. You are offered to change your 5 thieving groups level of risks, the more risk involved, the more money you can collect, and more likely your thieves are locked in jail, and when that happens you need to pay a fee so that the thief can become available again. Once your instructions are given, the outcomes are set, saving & loading won’t affect the results. Come back to guildhall after 5 days, you’ll know it by the overhead messages display :“Your thieves have returned from their missions."

Collect your money from Jariel, and possibly bail someone out of a jam, the quartermaster also awaits you next to Jariel for Renal’s due, if you fail to pay the quota, you lose your guild. Quotas for Renal:

1st time - 500 gold; 2nd - 500; 3rd - 1000; 4th - 1000; 5th - 350

Every time after the 5th is random:

50% - 500 gold; 20% - 900; 20% - 300; 10% -1000

Gameplay

 * To max out your returns, have all your first three thieves go for the highest risk (1 2 1)
 * You can charm the person give the Shadow Thieves' tribute to if you have the thief stronghold. Then take him out of the sight of any of your guildmembers, then attack him with no reputation loss. As long as none of your thieves see him die, you're fine

Event 1
Talk to Lathan, who's standing near Jariel, and he mentions that he is your "eyes and ears". He has nothing to report, but soon another thief, named Ama, appears. She wants you to help take out a government official. Simply meet her any night after this in Waukeen's Promenade. If you saved Kamuzu from the cells that Mae'Var kept, then he will warn you NOT to trust her. Gee, someone betraying you? Haven't seen THAT before!

Anyway, at night, wander over to Waukeen's Promenade. She'll appear and ask that you put your weapons away, supposedly to not scare someone. Yeah, her. Soon, you will be attacked by her along with 6 assassins. They have some minor treasures.

Event 2
Talk to Lathan again, and tell him to never let such things happen again. Then he has a bit of a problem, a pickpocket is keeping profits from you. Your fellow thieves know who is stealing but won't tell you.

You have to make your decision here and 5 days to get results: ~The guilty one is Darronal Gwin II~
 * Dock their pay - the thieves will killing the pickpocketer
 * Kill them all, kill the wrong one, or let Kretor fix it - Kretor will quit and you lose one of your best thieves, this will make getting your share much harder
 * Kill the right one - the profit skimming ends

Source & references

 * Baldur's Gate II Walkthrough by Dan Simpson