This is the executive officer,the XO and the second in command.You are there to replace the commander if he/she bites the dust so you are to step up to lead the marines to victory.They are also there to reassign marnes if needed to.You also have full access to the ship so you can may fill for other duties if it is understaffed.You are above all other staff but not the Commander. The XO is usually picked at the start of the round so have your preferences set and be lucky (or unlucky) to be picked.