Bad news for you: D:OS2 will not be like KotoR2 or MotB.
As far as I know, it goes like this: - There are 4 escaped prisoners and you create 1 of them. - You select a background for your char. - The other 3 companions will have backgrounds you have not selected for your char. (not sure how. is it random, can you select it, something else?)
So regarding one background, you can be this person, it can be a party member or you will never see him. It can be that you have background A and a companion has background B and when you play the game again it can be the other way around.
I think it will depend all on how your companions are selected and how they interact with you and the other companions. Since you are all escaped prisoners, you have a reason to work together. But you should have the option to abandom them and play alone. (Though I always used a full party in RPGs.)
By the way: Were EXP divided between party members in D:OS1?
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