There's definitely a little pitter-patter happening in his chest as he looks at Hange, then presses his lips to the back of their palm. Erwin lets it linger for just a moment, because perhaps the magic needs a moment to let it register, before straightening. There might be a hint of a flush rising on his cheekbones, but he just offers a smile-

...and apparently it wasn't enough.

"Ah."

Hange's conclusion really does only seem logical - they're all three of them stuck here together, so it would follow that all three need to be involved somehow. Levi's hesitation is plain, but despite his rather determined efforts to destroy the plant rather than trying its proscribed solution, he doesn't seem especially... put out, the more he watches him as Hange coaxes him between them.

Well that's...something. Yes.

And now having all three of them close together like this definitely isn't making his heart do funny little flip flops in anticipation, definitely not.

Without thinking, his hand has already floated to Levi's shoulder, steadying...although if he were asked, it's unclear which of them he was doing it for.

Catching Hange's eye, Erwin nods, although his expression is somewhat softer.

"Yes, together, on my count." Is this ridiculous? He feels a little ridiculous, but also a little...giddy, which just makes it extra ridiculous.

"One, two..." and he ducks down to leave a gentle kiss on Levi's soft, round cheek.