Callen is Cody's grandfather and the husband of  Cara Neal. He is a war veteran and a retired sailor. He knows a lot about Brindletown bay and may even have some slight connections to Alleu. Callen will not get a lot of screen time like his grandson. If you are fine with being absent in majority of the series but would still like to play as this character, for Callen is a very important aspect into the series to keep the plot going.  You are free to voice act as him.