Storm Raven said:
Nope. That's the difference between an enemy and an ally. If you cannot even figure out that distinction, then you are destined to never be able to understand the rules.
Clever, clever, clever retort. Doesn't answer the point, but there you go.
Imagine that you are engaged in combat, with one creature in front of you and another behind you.
Either (1) having creatures in these positions automatically provides flanking bonuses or (2) it does not. Posit: Since one or both creatures could be allies, it is demonstrably true that (2) applies.
Either (1) you must actively ignore a creature to avoid flanking bonuses or (2) you do not have to actively ignore a creature to prevent it from granting a flanking bonus to another creature. Posit: Again, the fact that you can have an ally as either or both creatures, without granting a flanking bonus, and without actively ignoring either demonstrates that (2) is correct.
Either (1) any non-allied creature in either position automatically grants a flanking bonus to any non-allied creature in the other position or (2) it does not. Posit: If (1), then a bystander provides a flanking bonus. Posit: If (1), then a mouse provides a flanking bonus. Posit: If (1) then a baby provides a flanking bonus. As this would be rather silly, I conclude that (2) is correct.
Conclusion: If you do not have to actively defend against a creature, such as an ally, a non-combatant (mouse, bystander), or an insignificant creature (mouse, housefly), it does not provide a flanking bonus to another creature.
Either (1) you are completely helpless against a creature you that does not provide a flanking bonus or (2) you are not. Posit: A bystander, ally, or mouse would not automatically hit you under these conditions. Posit: A bystander, ally, or mouse would not automatically coup de grace you in these conditions. Tests of Posits: Tell your PCs that they are flanked due to a mouse. Test of Posits: Tell your PCs that they are given an automatic coup-de-grace by a bystander. See how they react.
Conclusion: While you are not actively defending against any of these creatures, neither are you helpless against them.
Conclusion: The flanking rules assume that you are actively defending against creatures in both positions.
Posit: You can not actively defend against a creature that threatens you. For example, your ally can threaten the space you are in without providing flanking bonus.
Conclusion: If you are not actively defending against a creature, it does not provide a flanking bonus.
HOUSE RULE ADDENDUM: In the RAW it is not specifically possible to avoid actively defending against a creature that you are both aware of, and aware of as an opponent. If you allow a character to not actively defend, you must provide rules to model this.
Query: What rules best model not actively defending against a creature which you are aware of? Posit: This would be the same bonus given to a PC if they suddenly attacked an adjacent ally (changing sides during combat). Posit: This is best modelled by the flat-footed condition. Test of Posit: Have an NPC do this to a PC. Does the NPC automatically hit for maximum damage? Does the NPC automatically coup-de-grace? Why not?