Badboy
From Crusaderkings
"Badboy" is a measurement of a country's status among nations. Basically it's how much of a warmonger you've been. Aggressive nations will have high badboys while peaceful nations will have very low badboys.
While the game never lists the exact numerical score of your badboy (unless you search through your saved game file) it will list an approximation of it.
BADBOY IN-GAME DESCRIPTIONS
0 BB = We have an honourable reputation
1-2 BB = We have a respectable reputation
3-5 BB = We have a slightly tarnished reputation
6-10 BB = We have a tarnished reputation
11-15 BB = We have a rather bad reputation
16-20 BB = We have a very bad reputation
21-25 BB = We have an extremly bad reputation
26-30 BB = We are dishonourable scum
30+ BB = We are worse than Dishonourable scum
ACTIONS WHICH GIVE BADBOY
grab a title: 1BB
usurp a title: 0BB
take a title in an offensive war: 2BB
take a title in a defensive war: 1BB
a discovered assassination attempted: 1BB
a discovered assassination attempted against another ruler: 2BB
revoke a count title: 1BB
revoke a duke title: 0.75BB
force someone to yield a claim: 0BB
diplomatic vassalization: 0.75BB per province hold by the target directly, not including vassals
sneak attack, i.e. DOW while troops are in enemies territory: 2BB,does not apply to religious enemies
ACTIONS WHICH REDUCE BADBOY
grant a title: -0.5BB
create a bishopric*: 0BB, but you get the piety boost for indirect BB reduction
a successful assassination in your court: -1BB (this no longer is true for Deus Vult)
give up a title in a war: 0BB, but you get a claim on the title
yield a claim in a war: -1BB
VERY HARD MODE EFFECTS
On Very Hard mode your kingdom will naturally lose .02 badboy points per year.
Badboy reductions based on piety are calculated as such-
100 = -.18 per year
200 = -.36 per year
300 = -.54 per year
500 = -.9 per year
However, note that "natural" badboy reduction over time is capped at one point per year on very hard. Thus, a piety score of about 540-550 is needed to get the "best" natural reductions over time. Going above this, no matter how ridiculously high your piety gets, will NOT decrease your badboy any further. However, it will enable you to become Papal Controller during a Crusade.
New Kings and Kingdoms that conquer a lot benefit the most from high pieties. Old Kings and peaceful Kingdoms see the least benefit from piety score.
Note that badboy ratings above 10 often result in negative events (like vassals leaving your kingdom) so it's recommended to keep it below that level. Talented rulers must often balance badboy increases and reductions so that they can continue to expand without getting too high of a badboy score. Giving excess land to loyal vassals (especially to family members that you want to take over) is strongly recommended.
Vassals generally don't care how valuable the land you give them is- so save the best land for your best vassals and for your future Kings or Queens.
