으니

Since; given that

It gives the reason or the setting for whatever follows: we have had no breakfast and no snacks, now that the destination is locked in, in case it is a road we know. Several caption lines here use it as a cliffhanger instead, trailing off with there was one person who could not become a fairy, or there was a favourite to win, holding the reveal for the next beat. The everyday spoken equivalent is 으니까; one line is a fixed scolding frame, this damn zipline.

Register: neutral to bookish; the trailing caption use is a TV convention