Erwin is a little surprised when Levi leans backward onto his hand, but he keeps the pressure steady. Levi must be exhausted, to both give up on the idea of cleaning so easily and to also lean on Erwin like this.

"All right." Erwin smiles at him. "Then I better get some sleep too, since you'll be putting me through my paces tomorrow."

Erwin has been a helper during one of Levi's cleaning frenzies before, and delegated that job to new recruits as quickly as possible. With no new recruits here, he's just going to have to buck up and do the work himself.