Oh my, so many ideas! (I should say at the moment I'm looking for something small in scope. Up to date I have a lot of long threads, and I've found myself a bit overwhelmed when it comes to plotting out longer stories!)
Anyway, here goes. Don't know what appeals:
Rylzer: Since he does have a daemonic nature to him, we could do a little story involving some relic from fell. Maybe one Rylzer acquired through illicit means and is trying to sell off? Could have a little adventure exploring its nature.
Minerva: If she has a Mordecai linneage I imagine her family are grand duke supporters. Maybe she was visiting family or a potential suitor in Ahjfeld when it collapsed and remains as a 'guest'? Could do some domestic roleplay about how an estate reacts to its occupiers or something?
Petrin: I think the Starks and Wyndhams could have some pretty cool interactions, as they both seem to be smaller families trying to exist in what remains of Ahjfeld. Perhaps they're neighbors, or Wallund is unnervingly close to other lands Wylie grabbed? Maybe he tries to pressure Petrin into handing over resources to Turgall, or Petrin came across his nephews or something? Could be some drama and negotiations.