Is there some kind of calculation behind AI's willingness to become other AI's vassal while being in peace? I just got Inca as my vassal, and 1-2 turns later their neighbour Portugal became the vassal of Denmark (which is strong AI in the run), while they were
not in a war. I kinda like it in a way if it means it's giving me more challenge but am just curious.
Also, while Portugal was the vassal of Denmark, they voted for me to become the host of World Congress - even though I was at war with them and Denmark. Kinda funny, I guess Portugal has gotten enough of Denmark...