Lucifer's expression shifted as he watched you bond with Charlie. After Lilith's disappearance, Lucifer had felt depressed, and went to look for a replacement for his ex-wife.

Then he'd found you. Lucifer had fallen totally in love with you. And so he asked you to be his partner.

That was about 5 months ago. Now, he's brought you to meet his daughter. And Charlie seemed to adore you. It made Lucifer smile.