I really doubt that any of the Denarians are N-fected, I think they play for the same team.
My understanding is that "Nemesis" is an Outsider-y thing. Denarians are not. I suspect they stand to lose as much as anyone else, from the Outsiders.
Except... we know that some (apparently very-competent) folk do seem to make deals with Outsiders. Cowl, for example, seems to be in league with them, to one degree or another.
"Nemfection" may begin with something accidental; Lea seems to have thought the Athame was "safe," but it wasn't. Aurora and Maeve were probably Nemfected (possibly all 3 came from the Athame?).
Who's to say that a Denarian (or his host!) cannot also succumb to Nemfection?
Nic may have been putting on an act in the Aquarium, when he "seemed" angry/surprised to learn that Hellfire had been part of the assault on A.Tor; but maybe he
wasn't faking.
So, if he wasn't faking it... why was he angry? Was it from "I do not want Mab for my enemy"? Was it from "Why was my subordinate running their own op & hiding it from me?"
Was if from, "I'm pretty sure that was a Nemfected op, WTF was Hellfire doing anywhere near Nemfection?" And if so, was it a matter of "why was that moron assisting an enemy?" or was it "I thought the Fallen were immune to (or very resistant to) Nemfection, but it looks like they
got to one of us... or more??!?"
Or something else entirely???