The touch to his cheek instead of, say, the back of his neck is taken as a sign to yield and Levi pulls back to gauge Cecil's reaction. That uncertain expression is telling enough: he knows something's up. Cecil's not drawing back and the ease in which he's accepted and returned these kisses and touches suggests that he may be intimately familiar with these sorts of gestures from Levi. They've kissed before. Maybe more.

Cecil knows. He may not know what is wrong, but he knows that something's...

"Different?" he finishes for him, expression turning somewhat sheepish. "You know me well, don't you?" It's both a statement of endearment and a genuine inquiry. "Well, you were gonna find out soon enough so I'll tell you anyway--" Levi takes a deep breath as if he's about to reveal something Big and Important and an experience that's unique only to him, "I've been transported to the Future for some unknown cause. ... Or maybe Future Me has been transported back to the past for a wayyy more important reason and I've just swapped consciousness with my Future Self for convenience and I'm just supposed to fuck around here until he's done." A pause. "... Or, like, this is an elaborate dream sequence where I'm imagining a way hot future version of you who's totally receptive to my flirtations but is still taller than me for some reason."