Former Enemy Now Protectorate Still Enemy of My Allies?

[Martok]

-Why can't I stipulate that a nation that I'm at war with become my protectorate when offering a peace treaty?

I've been wondering this as well. It seems like an obvious thing to include (but maybe that's just me).

[Ardri]

I think it is tied to some other condition. I could not ask the Huron to be a protectorate in my French campaign to start the game, but at some point something changed and I now have the option. Now I have no idea what causes it to be available sometimes and not at other times. I've tried to figure it out, but it doesn't seem to be tied to common enemies/allies or anything dealing with relations to nations.

[Relic]

Yes, for some reason the pretectorates available varries throughout the game. Indeed these are annoying and confusing.