Following a discussion between @Affine and myself on one of my answers, I've found out the exact effects of the ambition personal trait may not be as simple as initially thought.
My claim: "Ambitious vassals always have a -50 opinion penalty towards their liege"
Affine claims: "Ambitious vassals only have a -50 opinion if they want something from you"
So who is right? How does the ambitious personal trait work, and when does it trigger a huge opinion penalty?
Best Answer
After some research, and vigorous testing at the labs, the results are finally in.
TL;DR: Affine was right, you can live in peace and harmony with your ambitious vassals. Presenting some evidence.
All of these guys are my direct vassals, and none of them have any inheritable claims to the titles they desire/want control over.
Experiments:
Conclusion:
This means, that you can have a reasonably good relationship with an ambitious vassal, as long as you keep him happy, and he doesn't have a claim to your titles. Depending on how you structure your realm, this might be feasible. However, once you have something he wants, you might rack up to -80 in negative opinion immediately (-50-25-5). This will make him rebel very fast.
Furthermore, I am almost certain that characters with the ambitious trait are more likely to plot and join factions against their liege.
Tips: