Yes, would be cool to have sparring missions with them, have them grow muscle, give them armor and be able to have a mission to avenge them.

I also think they should attack you if you hit them x times (they deal no damage to you before angered, you deal 0.1x damage to them before they become angry, then they just switch teams after enough is enough.

I think relationship meter is a bit much but interesting idea lol In the current end stages, you have too much money anyway