I agree that the normal AI can be a bit of a pussy at times, particularly when it ends up in more than one war. On the other hand, I have seen it be quite stubborn upon occasion as well -- mostly when fighting with a human player who has 20 or more badboy.
Ferocious AI is kind of a 'horse-medicine' cure though. From what I've observed, the ferocious AI will not make any unfavorable peace until all of its core provinces are taken, at which point it will get gutted. This is very bad for the AI's health as it is effectively incapable of bribing off enemies who are giving it a pasting; for a country like the Byzantium, who is surrounded by enemies, it is very dangerous indeed.
Far worse than the ferocious AI's inability to cut its losses, is its inability to take 'yes' for an answer. I've also found that countries with this flag set will not accept any favorable peace offer either, at least until they are offered something truly exorbitant, such as 2000+ ducats or 6+ provinces (often with the warscore strongly against them).
AI nations will typically end up eternally at war with a ferocious AI nation, unless they are in a position to smash the offender utterly or get smashed themselves. Playing against a ferocious AI nation as a human player is just annoying.
If all of this still sounds like a good idea, I'll give you a few examples of scenarios where there were significant nations with ferocious AI:
1) One of the earlier patches for the regular EU2 grand campaign had the Knights of Saint John and the Teutonic Knights set to ferocious = yes (crusader.ai). I had the Grand Dutchy of Muscovy until 1700 in that one because they were at war with the Knights of St John; no Empire of Russia even though they were eligable for it.
Fortunately, the Teutonic Knights would usually get mowed down by Poland.
2) The EEP had (and may still have for all I know) the ferocious AI for the Ottoman Empire during Suleyman's reign and the ferocious AI for Sweden during the Great Northern War.
Both were good ideas in theory... but let me tell you what happened in practice. After I played five games using the EEP, front to back, I had nearly the same results 4 out of 5 times.
Sweden was at war with the same people from 1698 to 1819. Three of those four times, he was almost completely covered by the end -- just once, he turbo-annexed over 15 provinces off of a colonial England who was doing well at one point.
The Ottoman Empire was at war from 1521 to 1566 in four of five games. Half of the time, this resulted in a total castration in 1567 (when the AI gets switched), the other half of the time he would peace out everyone by either giving or taking large amounts of gold/provinces.
The one time neither of these things happened was because I happened to be playing either the OE or Sweden.
Anyhow... blah blah blah blah, shame on me. If you're still reading this, I'd ask you to reconsider. I too wish that there was a stubborn = yes flag in the AI file, but unfortunately there isn't, and setting ferocity to true is like curing a hangover with a bullet.
Cheers and beers.
