Past-Unreal Conditionals (αν + pluperfect, θα + pluperfect)
A PAST-unreal conditional regrets or imagines a changed PAST: “If I had studied, I would have passed (but I didn’t, so I didn’t).” Greek puts the PLUPERFECT in BOTH clauses: αν + pluperfect in the condition, θα + pluperfect in the result - Αν είχα διαβάσει, θα είχα περάσει. θα appears ONLY in the result clause; the condition takes bare αν + the pluperfect. This is exactly the present-unreal pattern shifted one step further back in time: where the present-unreal used the imperfect for an unreal NOW, the past-unreal uses the pluperfect for an unreal THEN.
The rule
The past-unreal conditional imagines a changed past - a regret: “If I had studied, I would have passed (but I didn’t).” Greek uses the pluperfect in both clauses - αν + pluperfect in the condition, θα + pluperfect in the result: Αν είχα διαβάσει, θα είχα περάσει, Αν είχες έρθει, θα είχες δει την ταινία. θα sits only in the result; the condition is bare αν + the pluperfect. It is the present-unreal shifted one step further back in time - the imperfect for an unreal now, the pluperfect (see The Pluperfect) for an unreal then.