There are, of course, other Sin-Eaters who might have more concrete information around. Or there could just be Ryoji, who's been a Sin-Eater for so long now he doesn't actually really remember what it was like before Thanatos and is determined to make friends with all the Sin-Eaters. (They're some of the only people Thanatos doesn't fuss about at all, seeing as they are mostly OK people in his book. Thanatos has a very black and white approach to some things.)

"Hey!" Ryoji waves energetically at him, heading over once he spots him, "How are you?"