oops. human infected.
Well, as long as he doesn't activate any symptoms, it should be fine. maybe he could even only activate strengthening symptoms.
... Two side note questions though.
1. Seeing as how he can activate symptoms of hosts he isn't actively controlling, what would happen if he activated the lightning traits such as electromagnetic discharge under the use of one of the knights? I have no doubt that it would work, but how would the knight and their companions even react to one of their own suddenly discharging lightning?
2. if he took over the knight host for like, ten seconds, would their knowledge of language allow him to speak more fluently? he clearly gains such knowledge, seeing as how he knows how to speak goblin after taking over goblin hosts.