[ roy has no idea what keith's mom's name is, and so he doesn't recognize it. he only recognizes her as someone from their world due to her appearance, and the free usage of keith's name indicates a level of trust, but not much more than that. he also doesn't really pry into personal lives past casual conversation, so he really has no need or reason to know who krolia is, aside from someone telling him.

the training bit, though, and the smile vanishing, does cause a pique in his curiosity. krolia presents herself as someone trained, disciplined, and militaristic, and so roy will respond in kind: ]

I'm going to be frank with you, I have no idea who you are. [ better to just get that out of the way first, if she's spoken with shiro and them, and was mentioned. ] So I'm not going to make assumptions about what you know or don't know. It's good to hear there are more capable people in the Circle, though; Shiro's team has been an invaluable help and service to the Circle, especially to my people. I'm sure they'll be happy to have you around.

[ with a slight shrug of his shoulders. ]

It's always good to have more friends than foes, especially in a world like this. I'm sure the members of Voltron will catch you up to speed on what you've missed, in their social circles.