[Q]

Originally posted by Rollo:
Is this a standard or modded AI?

If "Will accept demand surrender from friend/enemy" (or something like this) is set to FALSE, the AI will never surrender no matter how high your score. You can check this in ..._AI_politics.txt file.

Rollo

Sorry Rollo, it's not about surrender. It's about accepting subjugation or protectorate treaties.
You can define the score for subjugation and protectorate in the politics.txt file but although the score is lower for these treaties than for surrender the AI will not accept these treaties as far as I have seen it. However he will surrender one or two turns later, which is not very logical IMO.