The VA does fight for a just, if self-serving, cause, and they do so ruthlessly: to wit, the practice of Requital above. The PCs are not evil but may go down this path in the interests of achieving some of their other campaign goals via the aid of the noble.
Basically, I'm looking to frame a game of difficult moral decisions and a lot of ethical gray areas. My post here describes the full situation a little better:
http://www.enworld.org/forum/showth...or-infiltrating-an-organization&prefixid=wotc
Ah, I see. OK, that's important information to have (as are the details about Tyr, the assassination of the Sorcerer King, and no slavery allowed).
So picking up at...
2. Feeling the PCs Out
Agent X is going to want to test the PCs' commitment to the Veiled Alliance, and ideally do it in an underhanded way, so that only at the last of a series of tests will the PCs be sure that they indeed are being tested. Using those motives of the Veiled Alliance you listed...
Test #1: "The Templar's Downfall" The PCs are asked to frame a Templar (former Templar?) for a crime. Agent X will not immediately reveal that this is actually so other trusted operatives of the Veiled Alliance can steal arcane lore from the Templar's home. While serving the Sorcerer-King, the Templar did bad things because he was ordered to, but also helped a lot of those who would be killed escape the hostile regime in Tyr. He's trying to live his life for the better now, despite the attitude towards Templars, and framing him would ruin the man, who is already wracked by guilt as it is. PCs can pass the test by doing as they're told OR by deducing what the real objective of the test is (getting the arcane lore from the Templar's house) and accomplishing that.
Test #2: "Justice for the Defiled" When a desiccated corpse is found in a suddenly dried well, Agent X informs the PCs that another agent of the Veiled Alliance has paid the ultimate price - dying for their cause to get evidence of a defiler hidden in Tyr. He wants the PCs to track down the defiler and bring him in for questioning, suspecting there may be an entire cult/cell of defilers. When the PCs do find the defiler, he is indeed as vile as the stories say, but he also knows about the plot of the noble the PCs work for, and threatens to reveal their true purpose to Agent X unless they let him go. PCs can pass this test by finding a way to bring other defilers to justice (falsely/truly blaming them for the murder & well-drying), killing the defiler and successfully lying about what they learned (it had better be convincing!), or finding a way to secure the defiler's silence and turning him over to Agent X.
Test #3: "To Divulge or Not to Divulge" The PCs are asked to bring in "tribute" for a ritual the Veiled Alliance is working on, though Agent X is elusive on the details, only stating that the tribute must be a regular stream of income not a one-time donation from the PCs. Soon thereafter, they meet another NPC (seemingly an influential power-broker) who expresses disdain for the current regime of arcane persecution, and wishes he could put his considerable resources toward a cause he can believe in. Of course, this NPC is a Veiled Alliance plant who is part of their test. Should they reveal their affiliation with the Veiled Alliance, they fail the test. If they manage to get the NPC's support (or even the support of someone else who has no affiliation with the Alliance) without giving away who they're doing the bidding of, they pass the test.
Test #4: "Not So Noble Now" As their final test, Agent X reveals he believes there is a hidden cult within the current ruling administration that seeks to restore the Sorcerer-King, and that So-And-So is a member. It just so happens that So-And-So is a close relative of the noble who hired the PC, and this draws the noble's own motives into question. Agent X's plan is to send the PCs to raid So-And-So's heavily guarded estate for evidence of his allegiance to the Sorcerer-King (and if evidence has been destroyed, to fabricate some and plant it). Complicating this assignment is that Agent X is going with the PCs. The noble warns the PCs that if they go after his relative, it's crossing a line, and he'll need to retaliate in kind against Agent X's family (i.e. insinuating he'll have Agent X's daughter killed). Passing the test will require a delicate balancing act and clever thinking.
EDIT: This was stream of consciousness. You might want to include more of
things look like ###, but in actuality it's all a set up by Agent X of the Veiled Alliance to test the PCs.