Just like any other group of people, the better you get along with each other, well -- the better you get along!
A group that treats each other respectfully is going to get along better than a group that's fighting all the time. A group that is interdependent and works for the group rather than being a gaggle of self-centered autonomous individuals who happen to share a body is going to work better together, rather than vying for time, competing with one another, becoming jealous of one another, etc.
The best way to look at this, both from an intrapersonal point of view and as a way to work with this in therapy is to view the internals as a family (you're about as stuck with one another as you are with birth or intentional external family members), and then to decide together what type of family you want to be -- do you want to be a family that functions well as a unit or do you want to be fighting with each other all the time?
- I find that working together does us a lot of good. We weren't always this harmonious, and we didn't always view each other as "family" of a sort...that's a much more recent revelation, but we always got along fairly well with each other. Viewing ourselves as a family has helped us understand when there are conflicts, and has firmed our resolve to work together on many issues that we might otherwise have wanted to neglect or put off. It also gave us a useful framework to figure out those problems in. We consider this a house, we have rules for it, we all live together in it, and in order to live and work together, we need to compromise, give respect, hear each other out, work on our issues quickly and REALLY resolve them rather than repressing them, etc. Just like any other functional family. -- XES