A question on dark cards where the victim gets either x or y.

Who makes the choice which is applied?

For fight cards: You play the card, read out the text, then hand the card to the player who you are playing it on.

They then read what happens if they choose X or Y and then they choose X or Y

Yes, I know that, but what about non-fight cards?

For Example Caprices card "They were screaming as they dissolved" says

Caprice gains two trauma or one betrayal and one rage.

Who chooses whether she gains trauma or betrayal and rage?

The player playing the card or the victim?

That would be the victims choice. I'm almost 90% sure on this. That is how I've always interpreted the cards when we play. Both outcomes usually suck, so it doesn't matter too much how you play it