As you may know, Terk is very unpleasant to you throughout your stay at Hero-U, because he doesn't like rogues.
As a matter of fact, around day 20 or so, he will ask you (or tell you) to spy on your head teacher, Master Urwald. He wants to know if Urwald has the Black Bird.
Now here's your chance to turn the tables!
After you either defeat or chase away the Drat Queen (between day 43 and day 46), see Master Urwald after class and talk to him about everything. You will mention that Terk wants you to find out about Urwald, and Urwald will say "Oh really? Why don't we find out about Terk?" (or something like that).By now you should have probably maxed out your lockpicking and sneak skills. So... break into Terk's office after midnight and find his book of transactions in the safe. Bring it to Urwald to complete the quest, and either make Terk nice or get Terk fired! Mwa ha ha!
Have fun with that little spoiler. (Or not, since I haven't actually spoiled anything...)