You might start seeing the caster as a friendly acquaintance, but once they start attacking your allies no matter how much you protest, your own feelings become suspicious and that would arguably become an Insight check (with a reasonable DC) to realize you've been affected by something strange, especially when you can't remember how you ever became acquaintances.
Your view of how the spell works and mine seem to differ a bit. If two of my friends are fighting with each other, I'd want to stop the fight - but I would not suspect I was drugged or hypnotized just because my friends were fighting. Now, if my friend landed a killing blow on another friend, that would be cause to potentially break the spell. However, the spell breakd sown as follows.
Once the charm person spell is cast (and the save is failed):
- The charmed creature can't attack the charmer.
- The charmed creature can't target the charmer with harmful abilities or magical effects.
- The charmer has advantage on any ability check to interact socially with the creature.
- The charmed creature regards the charmer as a friendly acuaintance.
The first is a prohibition on any attacks. This is a defined situation - so essentially if it requires an attack roll, the charmer creature can't do it to the charmer.
The second a prohibition on
targeting the charmer with 'harmful abilities or magical effects. This does not prohibit including them in an area of effect, per se, but before you can do that you need to consider the rest of the spell. Harmful here is a subjective term, but to me it really boils down to whether the charmed creature would feel betrayed by the action.
The third is self explanatory and not terribly convoluted outside of the inconsistent way in which charisma checks are used.
The last is the real cornerstone of the spell - you regard the charmer as a friendly acquaintance. They're someone you know (an acquaintanence), and you're friendly with them. My go to example is someone from work that you like, or a neighbor from down the street that seems pretty cool. Would you be ok catching them in a grenade blast? Probably not. Would you be ok collapsing a roof on them? I hope not. Would you be ok taking an extra candy from the candy dish on their desk despite the sign saying 'Take 1'? Maybe ... maybe not.
Regardless, if that friendly acquaintence were to attack a friend or family member, my first instinct would be to stop the situation and figure out why the attack took place. It would not be to suspect I've been drugged and brainwashed.
My general approach to charm person is to use it rarely on PCs in combat scenarios, and to give the PCs the benefi of the doubt when they use it on others.
