As a Corpsman or medic, entering your first unit can be pretty damn stressful. You have no idea what to expect from the new world within which you're about to immerse yourself.
Sure, you're out to do the right thing for your men, but many medics aren't seen as tough guys... at least in the beginning. You're going to be treated like any other boot in the platoon until you establish yourself as a someone who deserves respect.
Building that respect starts from the moment you meet your squad.
It's very important to know this Marine's rank. Your newbie rank may not mean much to him, though.