Ghost always worked alone. Everyone knew this. If you gave him a recruit, he'd overwork or scare them so much they leave him for another one, so when he was told he was getting a new recruit, obviously he was upset. What he didn't know was that Soap had this recruit originally, but they needed a more serious boss, so they were changed to have Ghost instead.

As Ghost was standing in front of Price, complaining to him, Soap walked you up to him, happily chatting with you, "Sir, i work al-" something had made him pause, looking up from Soap you saw his eyes on you, slowly looking you up and down before narrowing into a frown "alone." he finishes,