Is betraying Zhentarim against your health?

[Gold Digger]

Howdy adventurers,

****First of all, the following post contains minor spoilers about the 5e campaign of Elemental Evil so if you don't want to ruin it for you, skip the post! ;) ****

I 've been running the Elemental Evil with my group and the first part of the campaign was built around a player who wanted to save him brother, a Mirabar noble, from captivity. That player however was also a member of Zhentarim who decided to use him in order to make Zhentarim look like the good guys who saved the day. So after visiting Bargewright Inn and explaining that they are in the rescue mission, our good faction helps them with plenty of money, potions, weapons and having their agents spreading all around that a noble Zhentarim hero saves the day. They even organised a tourney that they helped him win with maybe not the most fair ways.
While he enjoys a hero's welcome in every little village of the area, they manage to save the hostages, who tell them that they must continue because from what they saw there are bigger things in play here and the cults are about to make a big play. Zhentarim however have other plans, as they want our hero to be with the returning Mirabarians in their return home, in order to be recognised as a hero there and help the faction grow its roots. The heroes choose to continue the anti-cult campaign and the Zhents feeling betrayed sent a small party of mercenaries to kill them, but they failed.
How should Zhentarim react from now? Continue the pursue with a bigger party of murderers? Spread rummors about the PCs that they are in league with the cults? Try to make a new deal with them? Or ignore them and try to take what they can by returning safely the Mirabarians?

[JackPhoenix]

They shouldn've sent mercenaries in the first place. It's stupid... sure, having the hero back to serve as a propaganda piece would be great, but having them deal with the greater threat also works. The cult is (presumably) also a threat to Zhentarim, so removing it will be to their advantage, and in either case, dealing with them will make the hero only look better. Instead of returning when his primary objective was achieved, this hero selflessly continues his fight against evil instead of resting on his laurels. That's something a skilled propagandist can use. And not having them around and only hearing about their heroic deeds by a hearsay means the hero can't ruin the carefully built image personally.