I tried to keep it to a minimum, but fair warning: this post will probably contain mild spoilers for three as-yet-unpublished stories, and will definitely contain information from Fatecraft, available in the archives of Darwin's Evolutions.
That's because this idea centers around the continuing adventures of Pazia and Vanchen, maybe six months after returning to her home city. (The idea to do a novel with the pair actually comes from the editor of DE, but the concept is definitely mine. ;-)) Perky, outspoken, idealistic Pazia is a dice-maker or daserii - that's a real term and I didn't have to make it up; sometimes, life is just that good to you - while insular, cynical Vanchen is a clockworker / inventor, half-Icewalker ... which means he has the ability to see things not visible by normal sight. (Quantifiable things like heat and depth, not supernatural.) Pazia's dice-craft has magical aspects, and she takes her devotion to chance very seriously.
Pazia has a brother. He's a lot like her, adding haplessly chivalrous and prone to shooting off his mouth. During his trip to the mysterious City of Lanterns, he met a six-veiled light-mage by the name of Kalliniar ... and when she comes to him for help, he recruits Pazia and Vanchen.
My idea is to set up Pazia and Vanchen as investigators. I'm undecided whether they've already started, or whether this will be their first case ... and how it involves the city they're living in, so it's possible that Kalliniar's presence will be tangential rather than directly related. However, the combination of these characters seems to present a perfect opportunity for a mystery story. Pazia and Mathory are the children of one of the city's most influential merchants, so they have a hook into the city's power structure.
If I have concerns, it's that what I've defined of the basic setting seems to require a fairly standard world. I can deviate from it somewhat, but anything else would make the other stories seem like sleight of hand. I also am not sure how to handle point of view. Pazia and Vanchen seems straightforward, but adding Mathory makes it potentially lopsided, and if I add Kalliniar - which I'm not sure I would want to - it becomes sort of cutesy: boy-girl-boy-girl.
Also, I have no actual plot yet ... but details, details.