The first thing to realize, you are already doing it right, since everyone is having fun.
Remember Drac is a sick bastard, and it's not hard to get on his bad side. If the players develop any friends, the friends can fall afoul of Drac and the cultists.
The real plot is players vs. Drac & the cult of the unspeakable one. You could let this develop slowly. Each session have one event that brings this on. Once the players are pissed enough, they'll want to hunt this cult down. If they run into money, have Drac send out the boys for a "donation to the lighthouse fund." Add clues (old books, carvings in the jungle, broken statues) about the Vallosans and how they fell, so the party starts to not want that to happen to them.
Ideas: Have cultists sell them "healing potions" that are poison. Have the cultists frame them for murder, and in order not to get offed by some gang, they trace it to the hidden temple. Give a prophetic dream where one of them sees the future world under the insane grip of the Unspeakable One.
If they players don't want to help Egil, let the cultists finish him off. Pick another NPC to respresnt Egil in the later episodes. If the players have an affinity for a certain bar or gang or whatever, have the cultists attack that instead of the temple of knowledge.
So basicaly, replace Egil and the temple with things the players decide they like. And if they don't like any NPCs, just have it all revolve around them, or have them caught up in the crossfire.
Twist: make their decision to not follow Egil a cunning plan. Egil is really evil, or already kidnapped and the Egil they met was a serpant person. "You are so lucky you didn't follow him into that death trap..."
IMHO, the cult is too much fun to just drop, but the pretext can be very different.
nhoj509 AT comcast DOT net
= Nhoj =