I lived this world almost everyday I was incarcerated in Florida State Prison, and the dynamic certainly was interesting.
What I noticed happened is each group first starts picking up on the speech patterns and mannerisms of the other and begins to emulate them. Without a doubt, this is a very important step for two-way communication to develop.
It does take a significant amount of effort to keep things from deteriorating though, and just if just one person in the group decides against integrating, things can become unstable quite quickly.