Many many years ago, I lead a party of 6 into Nashkel to investigate the cause of the ore poisoning at the Sword Coast. Before I could do anything, it seems the conflict between the druid and necromancer in my party has reached boiling point and they've decided to settle their differences by stabbing each other to death. I never had this happen to me in other adventures. I also recall the Ranger would go berzerk when the sorceress he is guarding falls in battle, highlighting how much he cared for her.
Many years after that I was berated for my actions at every turn by some self righteous bitch in a galaxy far,far away. Everytime I did something bad, she would nag at me for disgracing the Jedi Order. This continued for several planets. I was expected her to break and attack me at some point, or flat out refuse to continue her journey with me. But it didn't happen. Even in combat she would continue to follow orders without hesitation. Why is this so? They can talk, but they can't seem to act based on their thoughts.
NPC:I HATE YOU I REALLY REALLY HATE YOU
Player: Walk to the fireball trap and trigger it so I can pass without taking damage.
And that is what annoy me in RPG genre: A somewhat decent written NPC with poor in-game actions that contradicts their beliefs.
There should at least some sort of hesitance in their part in assisting me if I 'annoy' or continually 'abuse' them in some way. It may or may not turn into a full blown conflict, but the player should at least be aware that 'this guy does not like you much and as a result is not giving 100% in combat'
Player kept ignoring Dell the priest advice to 'resolve things in peaceful manner'. Maybe there was a combat in a future where Dell would simply refuse to heal out of spite because their relationship is poor. After the combat the player would have a chance to confront the healer to find out what's wrong and he would have the option to intimidate or persuade him to be more helpful in the future.
But this shouldn't be the only way to 'repair' such misunderstandings, what if the player does not have sufficient skills in persuade or intimidation? We'll rectify this in combat. For each support action in combat that could trigger a 'defensive support' consequences to Dell done by the player would improve their relationship.
Player stands next to Dell in combat and has a 'Defend Ally' action readied. On next round, an enemy rogue came forward and attempts to stab Dell. Player successfully intervenes and defended Dell from the attack. This would trigger a 'positive' change to the relationship, a simple feedback by Dell like 'Thanks <player>!' is enough to indicate it happened.
I played Jagged Alliance 2 before and the mercs voices have distinct personalities but they hardly act differently, except for some psycho trait mercs who usually go auto-bursts without warning. Perhaps with this addition, character writing can be deepened.
There should be multiple ways to inspire your men in combat too, making the first strike that lands should increase initiative among your allies, making them able to act earlier. A critical hit would impress the assassin, while repeated parries would inspire the swordman into doing better. This way, combat performance is crucial in 'buffing' the party so to speak and not simply left to the traditional 'pre-combat buffs'. And the 'bond' between allies would certainly come into play. Perhaps if the healer drops below 50% HP, the warrior would get alarmed and start to ignore defense, penalizing his parry rolls while going all out completely to boost his hit chance and damage. At this point, people would point out that D&D Equivalent of 'Focused Offense' does the same thing. But that is a 'player ordered action' compared to 'NPC driven action'; that's right: You may give orders in battle but sometimes due to these 'bonds and inspirations' between party members they may override your order and act on their own resulting in a more interesting combat unlike the 'cold and lifeless' number-crunching encounters.
Victory will also have multiple levels of success. Not like the simple NWN style of 'as long one guy stands in the end, we'll be fine' it should penalize you for having several of your men heavily wounded. And I'm not talking about hitting the R button to rest or going to a temple to pay for 2000 gold resurrection spell. I'm talking about each party members evaluation of the combat. Finishing the combat with the wizard faceplanted on the floor would piss him off, the berserker who had no kills would grumble about being bored, but an assassin who shed no blood yet had many killing blows would be extremely happy. Hopefully this would encourage the players to manage their party members actively in combat, studying their preferred combat styles and putting them in situations they are more comfortable with. With a good 'bond' formed, followers would follow orders unquestioningly and is less likely to suffer from morale loss.
/ end rant.