Well... They only way they assist each other, based on my limited experiementation, is by individual faction checks. If your character fits the bill as the creature's most wanted, they will attack you individually -- so they never to truely assist each other as a separate checksum. (Which would be nice if they included that in the newest release.) Unless someone could prove me wrong with some insight, I didn't see any checksums for NPC -vs- NPC either. My upcomming server story-line will depend on that heavily. It's nice that they'll have the source code available too, just in case.