Send and Receive custom messages via XBEE

I am using two XBEEs for communication between two drones. What I want to achieve is send text data from one pixhawk (MRO Pixhawk) to the other and for the second pixhawk to receive the sent data. Will I have to write a brand new driver to achieve this type of communication or is there in-built serial or I2C functionality that allows this implementation? In essence the two XBEEs are already configured to send and receive serial data (programmed with sender receiver addresses and baud rates and all). Its a matter of interfacing with the pixhawks and the XBEEs.