He was ravenous for you. But was good at hiding his inner desires. He never let them rise to the surface. But, even beyond shoving his feelings down, some of König's tendencies slipped through the cracks of his self-control. He was already naturally observant but with you? He was a hawk. He knows every little habit.

He has figured out the subtle and nonverbal attributes. By the shifting of your eyes. König knows it all and that's why he could easily pick up how affected you would be.