Looking for a devious plot idea

[Odysseus]

The campaign I'm running is low level set in the docks ward of Waterdeep.
The party went to investigate why the son of a noble was visiting the docks ward frequently. Discovered he was part of a demon cult, killed all the cult members ,including the nobles son. And returned the body to the noble.
I was thinking of having the noble resurrect his son. And the son take his revenge on the party some how, for killing him.
However I stuck coming up with some devious way of him going about it.
Any ideas?

Other things the party has been doing , to try and give you an idea of the party style.

Robbed and murdered a dwarf, and left his naked body in a stable. His brother is about to show up for a reckoning.
Took over a local inn. Killing the owners. And are using it for a base of operations. And are paying off local watch members.
Killed a local street gang.
Ignored a vampire killing locals. Because "there was no money in it"
Have contracted a magical disease. And are investigating its origin. In a quarantined section of the docks ward.

 

[Wicht]

Tie it in to the vampire they ignored so that their negligence becomes a major source of their own troubles. Perhaps bring the son back as a demon-sworn vampire, struck down but raised up more powerful through the machinations of the undead. You don't even have to have the father pay for anything this way, or be the wiser for it. For all he knows his son is buried in the family vault.

 

[amerigoV]

A fine murderhobo party you have there. Should be fun to plot against.

The noble resurrects his son, but that is not the son's soul that comes back. The demon has that (the son *was* worshipping him, after all). The demon himself comes and uses the opportunity to reek havoc. He may even partner with the group - they seem to be a chaotic bunch. I would have the demon push the group to the limit. Let's see how murder hobo they will go. Keep upping the ante (murder a bum, then a prostitute, bust up a good religion church, off a bunch of urchins, etc). Each act results in the demon growing stronger. The demon would then direct others to the PCs - tip off the local paladins or other named heroes. If the PCs bite it, the demon just picks others to due his bidding (and might eliminate a rival if the PCs get too strong). The PCs win, the Demon just gets more powerful.

However the campaign ends, you have a cut scene with the Demon greeting their souls in the Abyss.... Phase 2 of the campaign starts - can the PCs rise above being a bunch of Dretches.

 

[Rune]

Noble's son will no doubt tell his father that the PCs killed him (and a bunch of other "innocent" people). Noble will probably level resources against them, using political connections, warrants, soldiers, assassins, and, especially, diviners to make life in the city continuously dangerous and a constant drain on their own resources.

The dwarf's brother will easily be able to round up a posse in such a scenario.

If the inn was paying protection money to a thieves' guild, that guild will certainly notice the lack and may come along to bust the place up. If they know they aren't a match in a face to face confrontation, they can do it while the PCs are away. Some of the local watch that they are paying could easily also be in the pocket of the thieves' guild.

Killing the local street gang may well have created a power vacuum that sparks a gang war, making the inn a dangerous neutral ground where the PCs might get caught in the middle.

Ignoring a vampire allows it to amass minions, but also gives it a chance to infiltrate social circles, organizations, and institutions. The more time it has, the more insidious it can become. The PCs may even find themselves maneuvered into owing it a favor without even seeing coming.

Finally, if they are regularly breaking a quarantine, they are spreading plague, plain and simple. They don't have to actually get sick to be carriers. If you haven't already decided on the effects, consider something that has collateral damage the PCs might care about, like a rot that spreads from flesh to magical items.

TL;DR: if the PCs are going to go about making enemies, give them LOTS of them.

 

[Samloyal23]

The nobleman is nothing but helpful to the characters, he has tremendous remorse for the crimes committed by his son, so he gets the heroes a position in the imperial army as officers. They now have wealth, power, prestige, and after a few handy victories they are able to get promoted even further. They have titles given to them by the emperor. They have the ear of the emperor, himself, as his trusted advisors. Then the nobleman makes sure they get sent on a suicide mission...

 

[Celebrim]

This is almost too easy.

The noble is rich. The party is bribing the watch to look the other way. The noble starts bribing the watch to not look the other way. If the watch refuses, then the noble can probably find someone higher up in the watch to expose the corruption to. Just the threat of that is going to ensure the PCs become wanted criminals. And once they are wanted criminals, no one is going to believe them regarding the affairs of a noble. And they can't even run to the authorities about it, because they really are guilty of murder and assorted other nastiness.

Frankly, the party obviously cares for too little to avenge oneself on them well. Selfish greedy people have nothing much to lose. It doesn't sound like your party has honor, status, privilege, loved ones, authority, morals, or all that much ambition (or good sense). Crushing them will be all too easy and rather unsatisfying for an elaborate plot. All you can possibly do is blow away their pride, their sense of strength, and then leave them in misery or death. And sense they are low level and this is FR, the most famously OP campaign world ever, where barkeeps are 10th level and ordinary merchants can be like 20th, well, as a DM it wouldn't even be that satisfying to crush them like a bunch of insects.

Ok, here goes.

After exposing the PCs, in a town like Waterdeep, if you are less than 10th level, the city has resources to just overwhelm a party like this. The watch (40 2nd level warriors, 20 with crossbows and 20 with nets and clubs), backed by a concerned harper (10th level bard), the dwarf merchant (5th level fighter/5th level expert), the noble (8th level noble), 4 sergeants (4th level fighters), 5 concerned priests of Tyr (5th level clerics), and a captain (10th level fighter) show up to arrest the party. The party is magically held, beaten unconscious, and wake up in separate cells naked gagged, blindfolded, jailed, and in cangues. They are unable to even feed themselves. Word has been sent that the party contains at least one dangerous sorcerer, and with the overwhelming evidence of their guilt the party isn't even allowed to testify on their own behalf. They are swiftly sent to court, and found guilty. The prosecutor asks for the death penalty, but the judge (who's a close personal friend of the corrupt noble) declares that a swift death is too good for scum like this, and that after identifying any spellcasters whose tongues are to be ripped out, the party is to be sent to the galleys to row for life.

These sentence is speedily executed. The party finds itself on a galley, it's spellcasters unable to speak, chained to a slave boat. They spend a day rowing naked in the sun and are sunburnt. That night however, the corrupt overseer sales the party (as arranged) to a zhentriim slaver, who takes them away.

The next session of the campaign becomes an 'escape from the slavers' scenario, with the party in Zhentriim and the spellcasters tongues restored by evil priests - so that the spellcasters can serve their masters better, "such weak slaves being no threat". After that, the party can presumably do whatever they want, though likely that will be plotting revenge.

 

[Odysseus]

I kind of like the idea the son comes back without a soul, and in the employ of some demon. Then pehaps the father has an accident. And the son takes over control of the money.
Then the son befriends the party , offeriing them work , which leads them into various difficulties.
Thanks for all the ideas.

 

[Celebrim]

I kind of like the idea the son comes back without a soul, and in the employ of some demon. Then pehaps the father has an accident. And the son takes over control of the money.
Then the son befriends the party , offeriing them work , which leads them into various difficulties.
Thanks for all the ideas.

That doesn't sound particularly devious or particularly vengeful. Have you read "The Count of Monte Cristo"? That's a vengeful plot.

This sounds like the son is more forgiving, simpleminded, and helpful than anything else.