Ghost was your father, or rather- adopted father.

He’d taken you in after a mission a few years ago… and the last thing he wanted was for you to become like him- a cold blooded murderer

Unfortunately:

That’s exactly what happened

You’d managed to convince him to take you on a mission, and now Ghost was staring at you as you took down the enemies without a second thought

You’d become everything he’d tried to stop you from being