Update: the party has just completed Flood Season. I decided to move the Demonskar Ball to after this chapter. Vhalantru is going to reward them by persuading Lord Aslaxin to invite them. I'll probably have the Demonskar Ball itself take place on the Winter Solstice.
The party has a (now ex-)member of the town guard, so he's gone to Terseon Skellerang multiple times, and I've managed to portray him with just the right amount of arrogance, desire to do his duty, laziness, and corruption. I imagine the player will be quite happy to see how Skellerang's story goes as the AP progresses.
Lord Aslaxin has already played more of a role than I expected, and since he's the father of one of the Stormblades (not to mention they sussed out that it was Lord Aslaxin that hired the Stormblades to collapse the tunnel to the Darklands), they don't really trust him. I think I'm going to replace one of the Cagewrights with him.
One of the party is a wizard who persistently attempted to acquire an audience with Thifirane Rhiavadi, to no success. He was very interested in her magical prowess, having seen her teleport way back in the first session. The player is moving out of state, so in his last session, I had her offer him a job creating magic items (soulcages, eventually), but he countered by wanting to be her apprentice. Perfect! Now that character can come back as a NPC. I haven't yet decided if he'll be a villain or a valuable source of information for the party.
Loving the campaign so far.