“You were to finish this write-up last night – in fact, you should have finished it!” An expression of frustrated will, nagging in Latin is a borderline case between will and wish. In his New Latin Syntax, E. C. Woodcock discusses the use of imperfect and pluperfect subjunctive in a jussive sense (sections 110-111, 116), painstakingly distinguishing them from expressions of unfulfillable/unfulfilled wish. He doesn’t use the term ‘nagging,’ of course – but I think it is the psychology of nagging that opens the spaces for grammatical ambivalence. Here are two of Woodcock’s examples.
A nagging scene in Plautus (Rud. 841):
Quin occidisti extemplo? — Gladius non erat. — Caperes aut fustem aut lapidem. (Why didn’t you slaughter him on the spot?? — There was no sword… — You were to grab a club or a stone!
Cicero nags at Verres (Verr. 3.195):
Quid facere debuisti? Pecuniam rettulisses, frumentum ne emisses. (What ought you to have done? You should have returned the money, you should not have bought the corn!”
Nagging is generally a waste of time – one can’t reverse what has or has not been done. But it’s an effective roiling tool and a venting device. Here is a modern article on nagging:
Nagging is a term used almost exclusively by men to describe women. […] Men are not naggers. They’re assertive, they’re leaders, and invariably they’re passing on their wisdom – and gently reminding [others]of the path to take if they happen to forget along the way. Sure, they criticize, find fault, moan and complain, but it’s always for the [other person’s] benefit. The repetition of their advice, like “Read the map before you set off! How many times must I tell you?” and “Can’t you make more of an effort with how you look when my friends come round?” shows admirable persistence and, above all, shows that they care.