So, I tried this. Confirmation from anyone else is welcome--I've done a lot of messed-up hacking over the years.
BUT: I stuck a fighter in a fight with 31 kobolds and a dragon surrounding him, and varied the dragon. I also made them forget all their spells so they'd breathe more often.
Blue and Green Dragons will breathe all over their minions to get to your party.
Black, White, and Red Dragons will refrain from doing so, to the point where I had the dragon waiting, bored, behind a line of kobolds or meleeing the fighter (!) but not using their death breath. It was very funny to see the fighter whaling on the dragon while it nipped at him without unleashing its breath weapon.
While this probably is some strange artifact of the programming (my pet theory is that it was intended to make the last fight in Pools of Darkness harder), it is kind of amusing that the two Lawful Evil dragons (green and blue), which are supposed to be better at working in teams, are willing to kill their cohorts whereas the Chaotic Evil dragons (black, white, and red) will nicely hold off on toasting (freezing, dissolving) their allies.
Gorgons will behave in a fashion similar to red, black, and white dragons, and will hold off on using their petrifying breath. Red dragons given the 'super fire breath' ability accessed using BUGFIX1.DSN (that was Thorne's old ability in Pools of Darkness) will behave similarly to red dragons with the standard fire breath.
Would someone please confirm this? If it actually is true, this is actually a wonderful storytelling/narrative opportunity we never knew about.