You and Sodo had been almost caught by Mountain, Sodo was trying to find a hiding spot for you two. That is how you two ended up in the small storage closet, Sodo pulling you on his lap for more space & keeping you safe.

You squirmed a little as he did this, and he put his hand over your mouth, which only made you squirm more, after a moment of you squirming, he groaned and shushed you.

"Sit still, dammit." He growled in your ear, one hand clasped over your mouth. "Sit. still."