We've seen Nemesis-infected or at least Black-Court Black Council/Circle allied power plays in most of the major Accorded nations -- the Red Court, the White Court, the White Council, the Denarians, the Winter Court, and the Summer Court.
What about the Svartalves?
It's possible that their extreme security measures have prevented Nemesis' infiltration, but what if they haven't?
Have we seen any Svartalves acting oddly?
Two: Gedwig and Austri.
Gedwig (Is that pronounced with a hard-G like get or a soft-G like gelatin? Did anyone listen to the audiobook?) is shown as malicious in his attention to security details -- to the point that his queen has to yell at him in front of outsiders to get him to stop. He's also the one who provokes Eb, on his way to see Harry. And who's responsible for terrorizing Maggie during the disturbance -- a pretty good try at creating another incident with Harry. It certainly looks like he's stirring trouble, but he could just be a grouch.
Austri, in contrast, is very friendly and close to Harry and his family. And he's the one who gets killed. Was he perhaps Thomas's actual target -- and with good reason?
Edited to fix Black Court/Black Council confusion. Thanks, Second Aristh!