"Sounds like he really cares about you if he not only lets you feed on him but he takes care of you."

Because from the sounds of it he could have just let Su-jin feed with nothing more to it. The fact that he gave him so much more than that said a lot to him. But he was honestly glad that his new friend had someone like that.

"I did smell it. Including the fact that you had a regular meal that was the same person. It's how I knew you weren't human like me."