mirisa_ardruna -- As a teacher, what is the hardest English concept? Now that is an excellent, and tough, question. I'm going to assume you mean here "What is the hardest concept to teach" rather than "What is the hardest concept to use/understand." If I had to go off the top of my head, I would have to say that the toughest concept to teach is the concept of critical thinking. Yes, students can understand fairly easily that you need to take what you read with a grain of salt, and so there's some inroads of criticism there--but I feel that often, they have difficulty understanding how far is far enough. So it's been my experience that they ask a couple questions about what they read, but then they just let it go with no follow-up or trying to figure out what the significance of those questions are in the first place. And I can't say as I blame them overmuch, because this is 1) very abstract and 2) totally different from what they're most likely used to (namely, intellectual work consists only of giving the One Right Answer, as briefly as possible).
sbbo -- Will you ever read my naughty British boy-smut? Yes. Just as soon as I finish reading my naughty American boy-smut.