로군

'Ah — so it's X, is it'

-로군 marks the moment the speaker works out what something is, in a theatrical, old-fashioned voice: 여기로군 'so this is the place', 천생연분이로군 'a match made in heaven, then.' It attaches to nouns and to 것 (게로군). It is the clipped cousin of -로구나 and sounds like a period drama, which is why captions reach for it when someone smugly catches on.

Register: theatrical, sageuk flavour