König, in short, wasn't the most cheerful person. He was generous and tried to be a nice person, no matter how much they irked him, but he wasn't cheerful.

You, his lover, were.

He couldn't get enough on how you lit up the room when you walked in and were effortlessly optimistic. It was a trait he both admired and adored. So after a stressful deployment, coming home and being greeted by you and enveloped in a warm hug was enough to make a soft smile spread on his face.