"Huh." The explanation doesn't make a whole lot of sense, but nothing about their lives make any sense, so it's easy enough for Klaus to roll with it. His brother knows who he is, and already in this brief interaction has seemed more confident and at ease with himself than Klaus has seen in a long time.

Why would he be anything other than grateful for that?

"I'm happy for you," he says sincerely, giving Viktor a brief kiss on the temple and then draping an arm over his shoulders, staring up at the menu along with him. "Coffee's on me, from a them to a him."