Learn Romanian: Afară se întuneca repede și brusc a lovit tunetul. - It was getting dark fast outside, and suddenly the thunder struck.

This is subject-verb inversion, which is common in Romanian storytelling to create dramatic effect or emphasis. By putting the action (a lovit) before the subject (tunetul), it mimics the sudden surprise of the thunderclap. Saying tunetul a lovit would be grammatically correct but sound much flatter.

Why do we use the imperfect tense for se întuneca but the perfect compus for a lovit?

This is the classic narrative past tense split. The imperfect (se întuneca) sets the ongoing background scene (the fact that it was getting dark), while the perfect compus (a lovit) introduces a sudden, completed action that interrupts that background.

What role does the se play in se întuneca?

It makes the verb reflexive. The non-reflexive a întuneca means to darken something else, like when thick curtains darken a room. For impersonal natural phenomena like 'it is getting dark', Romanian uses the reflexive a se întuneca.

Could I put brusc at the very end of the sentence instead?

You could technically say și a lovit tunetul brusc, but placing brusc (suddenly) right before the verb strongly emphasizes the shock of the event. Combined with the inverted subject (tunetul), it creates a highly dramatic narrative flow.