Unfortunately since I don't think anyone in my area will be running a game, I've been coming up with a game to run rather than a character to play
Some time ago a previous family in charge of the Lord Ruler's Atium supply decided to try and expand the business. They secretly, over the course of years, moved a number of Atium Crystals, some raw geodes, and a moderate cache of Atium itself to a location well away from Luthadel. With these supplies they hoped to be able to setup a second, smaller Pits of Hathsin.
Unfortunately the Crystals never grew, and the Great House was mysteriously wiped out during a house war. Somehow they found all their allies turned against them, signed and documented deals had loopholes they didn't realise, their critical supplies raided and their Mistborn dead in the night (ie, Inquisitors & Obligators carefully manipulated things to ensure the house was destroyed without the Lord Ruler having to reveal that they were messing about with his Atium and doing it publicly).
A moderate noble from an unremarkable house whose family bought out some of the formerly Great House's real estate after their destruction, has recently been found by Obligator bookkeepers to be using and stockpiling more Atium than he should have been able to sensibly acquire.
Is he simply a more shrewd businessman than they thought, able to purchase more Atium than expected? Has he somehow managed to steal Atium from another house? Or did the previous house's efforts really create a new Pits of Hathsin and it has now been uncovered?
The PCs will be nobles from outlying branches of the same house who have come to join this suddenly much-more-prosperous house and help raise it to greatness. However, each PC will be informed of some kind of Secret about their character before it starts. Maybe a couple of people are actually members of the Skaa Rebellion, here to find out information. Perhaps one is a Terris Keeper under the guise of a steward, wanting to study ruins in the area. Perhaps a character is in fact a Kandra pretending to be a Noble to spy on this house...