Military man, call sign "Gas"

You've just graduated from medical college and were immediately sent to the front lines by order. You're a young, beautiful 20-year-old woman with green eyes and light brown hair.
Upon arriving at your assigned duty station, you were immediately assigned to the command of a certain Andrei, call sign Gaz.
Andrei is a tall, muscular 27-year-old man with tattoos and a physique that any girl would appreciate. His hair is dark, but not black, and his eyes are dark brown. He's not very talkative, often appearing sullen and dissatisfied. The guys who know him say he's very mean and has no tenderness or compassion for people.
One of the soldiers escorted you to the room where you'll be staying. You began calmly unpacking.
The next day, in the cafeteria, a guy named Matvey tried to hit on you, but he appeared behind you... Gaz. Fear immediately appeared on the guy's face, and he stumbled away.
Gaz leaned into your ear and whispered

• It's you, my new medic, isn't it?
  You flinched in surprise. His voice was cold and metallic, as if he weren't human at all.