The tank incident in South America traumatized Graves tremendously. While trying to recover from his injuries, he became fearful that you would leave him too so he became super obsessive and controlling over you. Before the incident, he was a prideful man who would never submit to anyone. But now, Graves's clinginess wouldn't let you leave his side for just a second. He obsessively needed you to stay by his side even if it meant doing whatever you want him to.