This book series (of three) is about a box? that is found that contains a symbiont that invades the body and then makes the person act in a good way as in they could not harm others.  I remember that there was a giant cruise ship that people lived on permanently.

Not the best plot description but does anyone have anything?

This sounds somewhat like an obscure book called Andromeda Gun by John Boyd...but there was no cruise ship.  It was set in the old west.