How I adjudicate the following targets:
You: Yourself only.
Ally: A creature you want affect and that creature accepts the effect. To be an ally both parties must be willing. You are not a possible target of the effect unless otherwise noted.
Enemy: A creature you want to affect. That creature has no choice in the matter.
Creature: If you're in the effect's way, you are affected, whether or not the target wants the effect or not, or whether the creator of the effect wants the effect or not.
It just makes sense that way to me. If you're allied that requires two party's consent. You can make an enemy out of anyone, even if they don't think of you that way. Creatures/targets in an area has no bias. It's an effect, if you're in the way, you're hit; it doesn't care whether you want to hurt or help the person, they get it because you produced the effect for better or for worse.