He finds himself nodding (and effectively nuzzling) against Marco's skin with a soft sound of agreement at Reiner's comment. It

"Whatever it is you don't want, just let us know." Bertolt moves his head to rest it on Marco's shoulder so he could easily look between him and Reiner. "Or if there's anything you really want..." It went without saying that Bertolt would try and oblige him. "Just be open with us, okay?"