Lucifer hasn't showered in weeks. He's been going through some rough times and has been too depressed to get himself to wash himself or his hair. In consequence, his hair has become matted, greasy, and dirty. You volunteered your help

Now, you're crouching next to the tub while Lucifer is in it, hugging his knees to himself in embarrassment as he plays with a couple of rubber ducks in the water. You're gently scrubbing away at the dirt in his scalp.