I have been running Curse of The Crimson Throne for a long time now, and there's one question that I've been putting off, and I can't put it off any longer. Because my players have finally assaulted the Deaths Head Vault, killed Cinnabar, and captured Koriantu.
Why do the Red Mantis Assassins do it?
What is in it for them to instigate a plague that kills thousands of innocents? (it doesn't seem very... assassiny, does it?) and why do they act against the one code they live by, - to never assassinate royalty?
I've been trying to come up with a good motivation for this, and I just can't seem to think of why they'd do it, aside from your standard motivation of money/power. Is there something I'm missing here?
They're no doubt about to question their captive, and I feel like I need better answers!
For MONEY, of course!
Certainly that's the classic answer, with a dollop of religious zealotry on the side to explain the rank and file assassins' reasoning, anyway.
And for most groups that's probably enough, given they just shrug and kill all the people with the funny bug hats, same as all the weird ladies with the scarred-up faces (Grey Maidens).
This can theoretically also work as the explanation if/when the PCs dig deeper into the Red Mantis motivations - "it's greed and zealotry, all the way down!" - but that's somewhat unsatisfying and makes the Red Mantis rather shallow as an organization.
So let's see if we can do any better than the inch-deep motivations as written.
For my campaign, the answer is politics. All of the Red Mantis that the party have encountered in Korvosa belong to one singular chapter of the Red Mantis, led by Mistress Kayltanya. Mistress Kayltanya is one of the Vernai, one of the highest leaders in the Red Mantis and presumably each Vernai is the head of their own chapter within the overall Red Mantis organization. However, the Vernai themselves have a boss canonically, Blood Mistress Jakalyn, who is even a step above the Vernai in assassination skill and personal power (i.e. I believe she canonically has several Mythic ranks).
Mistress Kayltanya wants to overthrow Jakalyn, and ideally would prefer to do it in a way that doesn't end up with her dead without warning due to Jakalyn figuring out what she's up to. That requires a base of operations away from the Red Mantis homeland on Mediogalti Island, which is what she's been promised in Korvosa by Queen Ileosa. For their help in her schemes, Kayltanya's chapter of the Red Mantis will be able to set up operations fully within the city, giving them their own base of operations separate from the rest of the Red Mantis power structure. And perhaps the use of some of the Thassilon relics that Ileosa has found along the way, which will help Kayltanya wage her revolution against Jakalyn and her traditionalist supporters within the Red Mantis.
As a result, this has justified Kayltanya "bending the rules" a bit, skirting the issues of messily killing people with a plague and providing the resources to poison the king to Ileosa, but not actually doing it herself, thus technically fulfilling the "no killing royalty" rule, to at least the bare minimum of that rule. This also explains why the Red Mantis stop coming after the PCs once Mistress Kayltanya is driven off - with her failure in Korvosa, Jakalyn decrees the contracts of Kayltanya's chapter invalid for the rest of the organization, thus letting the PCs off the potential hook of the Red Mantis coming after them for the rest of their lives.
For added complexity, you can have fractures within Kayltanya's own splinter organization due to her flagrant disregard for the Red Mantis's most important traditions - given her cleric levels and strong faith, Koriantu could even be the ideal source for this. Disenchanted by Kayltanya's ambitions and worried she could led to a more serious schism within the Red Mantis, Koriantu has been looking for a way out, conveniently provided now by her capture by the PCs.
Which would also give you a way to subvert their expectations, as they gear up to figure out ways of breaking what they presume to be a hardened assassination, only for poor Koriantu to immediately begin happily spilling her guts on Kayltanya's entire plan, motivation, and whatever else you'd like to info-dump on them about the Red Mantis/Queen Ileosa, all so they can in turn help her deal with Kayltanya and clean this mess up before Jakalyn decides to liquidate the entire chapter of Red Mantis to end the HERESY!
Of course, if you want to continue adding complexity and shades of grey to this situation, you can also info-dump details on how horrible of a boss and person in-general Jakalyn is, so maybe letting Kayltanya rip the Red Mantis organization down the middle with her little rebellion is actually for the best. But given Kayltanya has hooked her fortunes to Ileosa and is unlikely to deal with the PCs (and probably is not to be trusted, mountains of bodies under her feet aside) I suspect the PC solution will be to "kill 'em all and let their god sort them out."
1. Well, money and power are pretty good motivations for an assassin league. The PCs broadly kill people for money - certainly few DnD adventurers have problems with killing people and then looting the dead. The red mantis just make sure they get their payment upfront.
2. Like most cults, the Red Mantis recruit people who are poor, powerless, and in need. The Red Mantis offers them a family, opportunities to Excel, and to never have to go back to what they were in the gutter.
3. Killing is an art form to them - remember, taking cash to kill makes you morally warped - and the plague offers Dr Renier a new chance to practice his art in a new and interesting way.
4. In Korvosa specifically, the Queen offers them a large pile of cash, the sort they can't get elsewhere. And power, and opportunity. The tyranny Illeosa wants to set up lets the Red Mantis operate more freely. It would be easy to say that she's offered them a spot in the pantheon of the many, legitimising their religion. If they are an open organisation protected by the ruler, how many more new customers will be able to approach them?
The red mantis also do not assassinate the king. The queen does with the poison. They just provide it. I look at it as they were hired to do a job, the job is going south but they cannot get out because their word is their bond. If they went back and said oh well then they would be killed or worse for the failure they have provided.