I'm that woman, the one in sensible flats with a purple ink pen grading papers. I'm pretty sure every science department has at least one....somewhere along the way we've realized that purple is much less hostile than red, and if you leave lots of comments, it makes them easier to read. We also try to avoid large x-marks and emphasize the answers you got right.
I want to gouge my eyes out when you answer "true" to a multiple choice question and I may occasionally fling my pen across the room because you didn't even try to answer a question. If you use words like "malignant neoplasm" I cringe, because while I know what you're talking about, I'm not sure you do. When I look through your essays, I'm trying to figure out what you meant and if you were even close to being on the right track, while I insert commas and omitted letters. Sometimes I leave you sympathetic smiley faces when you slip up, and I do my best to point out your creative ideas as well as snark about your grammar.
Your papers drive me crazy because I'm on your side and I care so darn much that you get this. I'm hard on you because your learning is much more important than your grades to me. Eventually, I hope you feel the same way, because if not, you're going to have a miserable life. It's not about the numbers, in my grade book or on your paycheck. So we're going to talk about those things that you didn't understand, regardless of whether you'll be tested on them again or not. You're building a foundation, and the fact that you're in my class means that you at least claim to have some interest in pursuing the good of society at large. Get over the grade thing.
And seriously, if I have to fail you, I'm going to be just as upset as you are.