Her presence is greatly appreciated by the other guys too.
She is with the soldiers a lot trying to learn Vietnamese and constantly ask on visiting Tra Bong village,she swims in the Song Tra Bong river, even though there's a chance of ambush and snipers.
Mary Anne helps the medics when the the hurt come in, not scared of blood. She cuts her hair and stops putting on makeup and jewelry. after a while she is taught to use a M-16.
Mary Anne still loves Mark Fossie, their love life become complicated.