
Who in their right mind would kiss a person’s neck they meet for the first time?

Someone who probably didn't meet him for the first time. I'm guessing, as many other guideverse ones, he's someone he has known since childhood or probably before he became SSSSSS level threat or maybe something else entirely, maybe he awakened because of him, but it doesn't seem like a first meeting.
This is No reason 2.0 fucking shit