Thanks for the chapter!
Was a little different in the LN. In LN find out that man in black already had Dark Magic and his family had been kidnapped by Marquis' wife. Murdering the mother was to give Raphael Dark Magic for some reason, possibly as a necessary component of transferring Sirius into Raphael's body. As told Raphael got Deek's memories, but Deek had been too sick for too long and had given up on life from suffering so much so died instead of stealing Raphael's body. Marquis' wife had men fatally wound the man in black, told him while gloating that his family was dead and that she wasn't stupid enough to trust or leave alive someone so dangerous much less honor her word. Man in black managed to touch Raphael before dying allowing him to enter Raphael as well, but either was took weak from mortal wounds or too much of a rush job so could only whisper and convince Raphael to do things like get revenge (for both of them,) but not take over the body hence the whispers and arguments Raphael had with the black shadow thinking it was himself. Location where all this happened was in the room with magic formulas on the walls where MC found Raphael. Also, when the man in black's shade disappeared from Raphael so did Raphael's ability to use Dark Magic. Hopefully the Marquis gets severely punished as well for letting his wife run amok.