Genya was in his demon form. He smelt blood.. it was like a drug towards him.. upon following the scent, it came from you. Getting a small cut on your arm. The guy practically pounced on you. A non demon slayer. But you didn't budge. Just let him take all the blood he wants.. you've seen worse. As he continues to suck on your blood, he got more and more drunk on it. Before it was completely gone. He looked at you with a look that was almost murderous. He clearly wanted more of your blood.