Mephisto

"H-How do you know them? How do you know their names?!" Damian Rose exclaimed to which the shadowy figure replied with a toothy grin on his face. "I think that you already know the answer to that question of yours, Damian. It is because I am you, and in return, that makes you, me." 

Damian Rose was already shivering in fear as his lips quivered in shock of it all. "I want to get rid of you. I will get rid of you, you piece of shit! You are trying to hijack my body, right? Then I will give you no semblance of a chance at all whatsoever!" Damian Rose exclaimed as he threw punches at the shadow figure.

But his punches merely phased in and out of the shadowy figure's body. He was not getting hit at all by Damian Rose's punches and he flailed wildly at the figure. All he heard in response was laughter, a laughing sound that the shadowy figure made. It sounded like he was mocking Damian for his inability to even damage him.