He knows where this is going, and where he'll end up, but letting the moments stretch out has a strange sweetness to it. Letting her lead and watching from a step away, letting her wet her hair and savor the water for a moment by herself - it's one more moment when he can see her looking relaxed and content. And so he hangs back, admiring the view and letting Scully decidee just when she wants company.

Of course, as soon as she commands him, he's stepping into the shower, wrapping his arms around her newly slippery body and pulling her into an embrace, his lips landing for a moment on the crown of her head.