Miss Emily is Hailsham's stern head guardian. Picture your traditional strict schoolmarm: grey hair, terse sentences, intimidating as all get-out, seems to shoot laser beams out of her eyes, the whole deal. Then add to this the fact that Miss Emily has some super sensory Mad-Eye Moody abilities to see everything that goes on in Hailsham, and you'll really get the picture. Kathy tells us, "It was like she had some extra sense" (4.26). Don't even think about throwing that paper airplane in here.
The idea of getting scolded by Miss Emily may be nerve-racking, but she's also the one keeping Hailsham students safe. In fact, these two elements go hand-in-hand. Once again, Kathy says it best: "We were all pretty scared of her and didn't think of her in the way we did the other guardians. But we considered her to be fair and respected her decisions; and even in the Juniors, we probably recognized that it was her presence, intimidating though it was, that made us all feel so safe at Hailsham" (4.10). In fact, Miss Emily works so hard to keep the students safe that she, alongside Madame, lobbies for Hailsham students to be treated like regular humans (at least until they donate, of course).
There's one more thing that makes Miss Emily intimidating: she controls all the information. She's got some pretty specific ideas on what Hailsham students should know about their future (hint: they should know basically nothing) and she's not afraid to fire any guardians who don't agree with her. Check out more on Miss Emily's views in the "Lies and Deceit" theme and see if you agree with her wily tactics.