Give him a moment while he tries to rationalize what in the seven hells Ritsuka just said, because that was a lot.

"You... didn't meet the one from your realm, but a Waver from an entirely different realm...?" He thinks he gets it being somewhat aware of you know other timelines but for as infrequently as his tone has changed in their conversation the slight curious upward inflection towards the end felt like a deafening shift.