The Enemy slips into the group under disguise, hangs with the other PCs (since the PC hasn't shown up yet in game to interact with the Enemy) and starts teaching skills and such.
PC 2 gets into argument with Enemy, and attacks Enemy. Enemy escapes.
Later Encounter: PC 2 takes first opportunity to attack Enemy.
So, even though PC 2 hasn't taken the NPC as an Enemy ... should the NPC actually focus some attention on PC 2 as well as the PC who took points in the NPC? I'm thinking so. Now, in what manner, I'm not certain yet, I'm still thinking the Enemy should go the subversion route (social attacks), rather than wanting PC 2 dead. They'll still have an interest in the PC who took points for them, but that PC has yet to actually attack the Enemy. PC 2 seems intent to kill.