personally if the person fails the save i make them immediately consider the caster a long lost friend. details of the friendship do not exist and pressing too hard may break the spell but the target basically goes "Oh! hey buddy its been a long time." or something like that
AND THATS IT
I ignore the rest of the spells rule text because it can become tricky.
the caster can talk to or ask the target things just as any old friend would and the target may say things like "dont you remember what the boss told us" but I wont make the target do or say anything he would not do or say for a relatively good friend.
also just because the target now considers the caster a friend does not mean that he considers his allies as his enemies, or that the caster is now at the very top of the targets list of important people.
so the target is not likley to knowingly betray his allies and will still usually side with and obey his leader more than the caster in the same way a soldier would usually obey his commanding officer before an old friend (at least when the commander is present.
having said that every situation should be a little different. as the GM create a quick and dirty personality for the target and play along.
I have no problem with the target failing it's save. What I'm trying to figure out is the casting of the spell.
Can people see the casting?
ie. Can you hide the casting of it?
How would you go about it? I'm assuming a bluff check would do (or maybe a stealth check if you're trying to hide the casting?)
Would the person know you're casting if they don't have spell craft?Then what happens if the person makes his saving throw?
Does he know something was cast on him?
It isn't as easy to conceal as you hope... but the good news is, reacting to it isn't automatic.
"Spellcraft
(Int; Trained Only)
Identify a spell as it is being cast 15 + spell level
Identifying a spell as it is being cast requires no action, but you must be able to clearly see the spell as it is being cast, and this incurs the same penalties as a Perception skill check due to distance, poor conditions, and other factors."
So, a target can only recognize a spell being cast as a charm person if he or she is trained in spellcraft, the DC would be 16 plus any applicable penalties for distraction (+5) which a bluff check could help with, or an accomplice, distance (+1/10ft), Darkness (unfavorable or terrible conditions +2/+5 GM's call). Which means, a prepared-concealed caster with someone distracting his target could enforce a 29DC spellcraft check to identify a charm person (30ft away). Which someone without training in spellcraft can't attempt at all.
There are some abilities that can conceal casting, the Bardic Music Feat 'Spell song' for instance. Still spell would limit the components to Verbal only which 'should' make it easier to conceal (DM call)
Succeeding on a Saving Throw: A creature that successfully saves against a spell that has no obvious physical effects feels a hostile force or a tingle, but cannot deduce the exact nature of the attack.
If your target makes his save, will not be able to identify the source of the "tingling" unless he made the spellcraft check before.
Most likely cause is the target will suddenly shift to "suspicious" of all people in his presence, or one category worse than starting.
I think that if some one is trying to hide the casting then as noted above there should be a spell craft and/or perception.
only difference between me and MC is that I dont think it should all be rolled into one roll. I believe that there should be an opposed perception sense motive vs bluff if the caster is attempting to hide the casting in an observable spot. if the perception succeeds THEN there is a spell craft if the observer can spell craft.