Quote 1
"May I creep up here at night, whenever it is safe, and hear all the things you have made up in the day? It will seem as if we were more 'best friends' than ever." (8.75)
Ermengarde is even willing to risk the ire of the very scary Miss Minchin in order to keep up her friendship with Sara. She may not be smart or pretty, but she's a really good friend—as good a friend as Sara herself is. Which makes her a princess of her own, right?
Quote 2
"Sara," she said in a timid, almost awe-stricken voice, "are—are —you never told me—I don't want to be rude, but—are YOU ever hungry?" (15.99)
Well, duh, Ermengarde. Duh. But we can't really blame Ermengarde: she's a loyal and true friend, but she has literally no imagination. If she's not hungry, she can't imagine that anyone else would be.