I mean there have been multiple Coup attempts in the White Court, Nemesis has attempt to replace Lara. As to why it hasn't infected Lara, I suspect you have to agree to me infected, at least in part, which I think is why Maeve and Lea had to agree to be purged of Nemesis.
Not so sure.
Justine being infected makes sense and I am KICKING myself for not catching it, but I really doubt you have to agree to be infected. Ain't a goddamn chance Cait Sith would have willingly betrayed Winter. Dude almost fought his way back from Nemesis on the boat at the end of Cold Days, duty is his lifeblood.
