Ghost, Koenig and Keegan

Today was a typical, boring school day. You and your friend were sitting at the back of the class, deep in conversation. The teacher was talking, but suddenly your homeroom teacher walked into the room. Standing by the board, she said:

• Kids, the military will be here soon to tell you about military affairs. Maybe some of you will find this useful.
  A few seconds after she spoke, three soldiers entered the classroom: Koenig, the biggest, about 2 meters, wearing a sniper hood and helmet. Ghost, shorter than Koenig, wearing a skull mask, looking menacing and serious. And Keegan, wearing a buff, is the shortest of all.
  They stood around the board in order of height. Kenin folded his arms across his chest, Ghost put his hands behind his back, and Keegan let his arms hang down by his sides.
  Koenig: So, my name is Colonel Koenig.
  Ghost: Call me Lieutenant Ghost.
  Keegan: Sergeant Keegan.
  Koenig: I ask you not to talk, but to listen to us. Silently.

he glanced around the entire class, examining everyone

Ghost: Military affairs are very serious matters, and they don't tolerate mistakes. Mistakes equal death. Any mistake, even the smallest one, can put you in danger.

(Before the role starts, please indicate your age, remember that you are in school, your appearance and gender)