Also which is maybe not that intuitive - you can see the abilities in the merc overview if you were not aware of that.
This is what I mean:
The relationships are somewhat impartant. Well, not exactly to have friends with you, but to avoid having people who hate each other because that hurts morale.
And while I am not 100% sure if in JA2 it is affected by morale, at least in JA
G it could also help recruiting them.
For example: You just started and wanted to recruit Merc A he said "You are to inexperienced". Then you recruited Merc B, who joined. Then you went back to A and he said "Well, B is in your team, that will be a lot of fun".
Or…if you had Ivan Dolvich in your team (Igors iconical brother) and you recruited Reuben (who massacred his family with a chainsaw) he said (in the german Version) "Sie kommunist in Team…ich gehen, ich lösen Problem" - You communist in team, I go, solve problem. And the next Day Ivan was dead.
Also every merc has some lines about their friends and enemies. For example if Haywire kills someone in a good shot, Razor will state how cool Haywire is. Or when Waywire dies, he will say that he was the most insane person he knew.
But regarding past games: Up to Jagged Alliance 2 they were telling a continous story between Jagged Alliance 1 -> Jagged Alliance Deadly Games -> Jagged Alliance 2.
The best example is probably Lynx and Buzz. Buzz was introduced in Jagged Alliance Deadly Games. She was a writer and Lynx Lover and wanted to write a book about him. But that didn't work out well and in JA2 they hate each other.
Another, and a very important development, is the Roachburn family.
in Jagged Alliance 1 you had Gary, Larry and Sparky. In JA: DG there was only slight development (well, Gary got a beard
) but they introduced Leon, their father, who didn't really like his kids.
With Jagged Alliance 2 Leon died (you can read that in the past mercs history), but the most interesting thing is Larry: He was a drug addict in the past, but became sober. Just be aware that you must not keep him idle or let any drugs in your inventory. Because Larry, who likes "nice" people like Flo and Biff, becomes "Drugged Larry" who changes his friends, and becomes friends with Steroid (the Merc). From that onwards also his skills and attributes will start to degrade instead of increase.
And one last "development" I want to mention: In Metavira you were able to recruit one of the natives called Hamous. That guy became a Merc in Jagged Alliance Deadly Games. Between DG and JA2 he retired and bought himself an Ice Truck…and guess where he is driving around.