I've done quite a bit more testing, and what LB has said rings true (30+ combats). If 'is friendly' is checked, the only way an NPC will attack the party is if you attack her first. Alignment and pre-gen are not factors.
Character control of NPCs or monster marked as 'is friendly' depends on the paladin being in the party even if there are other characters with high charisma. Now, if you make an NPC pre-gen and add them at party creation, that's a completely different story.
