[Jerr Conner]

As for blasting party members, I usually play under the assumption that I want my party to continue as-is; i.e. they are not out to kill each other (or if they are, they will not succeed until I deem it appropriate). Thus, I tend not to use spells that will harm friendlies. However, it's certainly valid RPing to have a mage throw fireballs at his party if he has no concern for them. (Or you could have a neophyte mage who constantly makes "mistakes" in casting.) But it is not invalid RPing for such a mage to not throw fireballs at his party. Thus: In practice, handling battle scenarios is up to the roleplayer.

That's a good way of thinking about it. Sometimes I can't avoid hitting my NPCs, so I have to throw a fireball. (Usually it's just Aerie trying to take Jaheira and Viconia out of the competition )