Masters not aiding vassals?

[gaash2]

last game I just finished Pacal was running away tech wise and even killing everyone other than him and his vassal (Sitting Bull) wasn't enough for the diplo votes or domination. So, I decided to just try attacking Sitting Bull and capture his cities for votes. Interestingly, despite being a vassal of Pacal, Pacal didn't start attacking me (or any of my 4 vassals). He just pillaged some improvements at sea and used his bombers on some of my cities.

Is this normal behavior? Is this a cheesy exploit of sorts?

 

[Fippy]

It's somewhat normal, AIs are often not doing much when not starting wars themselves or having a big SoD ready.
If you were so much stronger, he probably kept his units for defense.

 

[rah]

Yeah, info is always king. Knowing where their SODs are makes it a lot easier to anticipate/manipulate the AI.