Bad Blood System
This would be a subsection of reputation. IF other mercenary companies were implemented into the game, the Battle Brothers might find themselves fighting groups of the same occupation but different employers on some contracts. Some interaction with these groups could create enmity and competition between the two bands. That’s assuming that their entire band wasn’t wiped out though, which makes me think…
If I was a bandit on the losing end of a fight gone wrong, I might be convinced to drop my weapon and surrender. Brothers might initiate a capture by surrounding a human enemy on all hexes when said enemy is of low morale. Bandits might be given over to jailors in town for a price or a rep boost. When fighting other human groups that aren’t on the bad side of the law, perhaps the survivors could ask for peace. Peace terms could include certain terms (The right to strip the dead on the field, gold, etc). If a group of brothers is fighting guards, or another band of mercenaries, then granting lenient terms could be beneficial for reputation, while demanding a lot would create some enmity. Mercenary companies let off with a slap on the wrist could be friendly towards the Brothers in the future, while those who are denied certain dignities in a truce may turn hostile if they rebuild and see the player on the map. Of course, it wouldn’t apply to orcs, bandits and things that bump in the night. They just want to eat your gibblets come hell or high water.