What was the theme of this trilogy?

Here are some ideas since I go first. Notice the importance of relationships in the major characters' lives. Jack, Melli, and Tawl really lack good relationships. Melli starts out close to her dad but enters into serious conflict with him and is left without anyone until she meets Jack. Jack has no deep emotial connections with others at the begining of the series but I think his friendship with Melli creates an incentive to presivir in order to help her. Tawl was an emotional wreck until he met Nabber.

And Baralis and Crope need each other. The only character that didn't have a friendship was the Archbishop of Rorn. But he has an empty life.

So what do you all see as the central theme? Or side themes too?