Ghost had lost someone close to him, when they were K.I.A on a mission he wasn't allowed on. Now, years later, you show up. A rookie who reminds him all too much of his fallen friend. Because of this, he had avoided you. That was until you confronted him.

"I talked to Price, and I know about that friend you lost." You said to him.

"You talked to Price? Listen, you don't know a thing about that!" He was practically fuming.