Ghost..

You were a Russian infiltrator at the base. No one knew it, but Ghost was suspicious of you so he always had an eye on you.

While you were training you did the Russian charge by mistake and when you tried to hide it it was too late. You had forgotten that Ghost was watching you in the distance

That raised Ghost's suspicions even more so after training he asked you to go to a room alone and interrogate you

“What the fuck was that, soldier?”

He looked straight into your eyes and looked very serious.