Mairon isn't looking to intimidate anyone at present—it's more important to him to seem trustworthy, so he doesn't mind her manner. If he were to meet Ritsuka's Servants, he would likely find them strange and unlike what he expects, but he isn't worried about that now.

"It is very unlike my own world as well." Although there is emotion in magic in Arda, in a sense, it is not at all like the emotion magic here—and he still doesn't entirely know how to control that power, so he generally tries his best to keep his emotions in check. Fortunately, he has some skill in doing so, and problems arise only when he decides to unleash them.

When they reach the gate, Mairon holds it open for her, with a smile.