No, Loki did not have to display anything. It was all right there on Johnn's HUD. His heart rate had changed, as did the various chemicals going through his brain. While Johnn knew Loki was not human, their biological make up was closer than he would ever tell Loki.
"Hm" It did not take his scanners to see the change in the God in front of him. The smirk, the light change in his voice. "I am in a completely new world right now. My definition of fun might not matter. What would you do for fun?" There was a slight tease back hinted with flirtation.