NOTE: I am actually taking this class in Spring 2018, not Fall 2017. I'm commenting here for my introduction because as of now there is no Spring 2018 introduction thread.
My name is Will Lestrange and I'm a fifth year Slytherin Prefect. In addition to Career Advice, I am also taking Gobbledegook, When Muggles and Magic Collide II, and Treasure Hunt while continuing on with Astronomy from the fall. Of course, I'm also sitting my OWLs: I already have taken five of the six fall ones and plan to take at least four spring OWLs this time around as well.
People who haven't specifically had me in their classes tend to know me from Quidditch: it was the thing I most looked forward to when I signed up here nearly five years back. Indeed, not only am I a captain of my House team but I even have been sitting on the Quidditch Board for the past two years! This gives me crucial practice with leadership skills - which I feel can only be more useful as I draw closer to graduation. Fun fact: I was recently deemed Mx Slytherin for 2017 - and learning who "Judge Nickleby Duckling" was (as well as enjoying his comments) made me decide that I really want to take a class with him... so here I am right now!
After I finish my magical education? Slytherins should be ambitious and goal-oriented but I'm at a bit of a crossroads; although I think I have potential as a professional Quidditch player, I know that no one really does that for more than about 10 or 20 years. So I need to think of something to do long-term when I'm too old to fly as fast as I do now. Maybe some prestigious position in the Ministry - say - as an Unspeakable? I'd say "Minister of Magic" except for one small detail: Ministers of Magic tend to serve more as figureheads than have any true power in their own right.
My favorite magical subject is Charms because it's always well-taught and the spells taught are very useful (and stretch my magical repetorie). The subject that I find the most difficult is Arithmancy, at least the way it's taught at school: while I love working with numbers, school Arithmancy seems to assume everything is a zero, one, two, three, four, five, six, seven, eight, or nine... and assigns each of those numbers very specific meanings which don't seem to square with reality! Having to pretend so many numbers don't even exist - and deny what I see around me to fit what the charts say - makes Arithmancy particularly hard.
One last thing that may NOT surprise you: "Prefects Who Gained Power" is my favorite bit of bedtime reading (at least in character

)... you'll recognize my bed in the dungeons because it's the one with "Prefects Who Gained Power" by the pillow and Malumbrabas the Lethifold waiting atop the bed to serve as my topmost blanket!