“Nemesis,” she breathed. “Speak it carefully—or it may hear you.”
If Harry is talking to Mab; or anyone else clued-in about Nemesis, and the conversation involves the strategy and tactics needed to defeat it or its aims, I can understand that keeping Nemesis from listening in on that conversation would be a good idea. However, by now Harry has had two open conversations with the Nemesis personality of one of his friends and one of his allies. Those conversations weren't exactly subtle. Nemesis knows that Harry knows about it. So now, shouldn't Harry be able to warn his friends about Nemesis without worrying that it may hear him?
I thought the risk of doing this is that a Nemfected individual would react to finding out that Harry was aware of Nemesis by trying to nemfect Harry. But Harry must already be on Nemesis' hit list. For example, if Will or Georgia has already been takin over by Nemesis, wouldn't they already be looking for an opportunity to do the same thing to Harry. Conversely, keeping his allies in the dark makes for having less effective allies. Even if Harry held to using the term Adversary, the risk of talking about it doesn't seem any greater than the risk of not talking about it. What do you think?