The trick that follows is a simple yet effective Royal Marriages effect using the Rusduck Stay Stack principle. A Stay Stack is a mirror stack that retains its properties after certain shuffling.
1. Remove the four Queens and the four Kings and arrange them in a mirror stack, paying attention only to the suits. Here is an example of a setup:
KC-KH-KS-QD-KD-QS-QH-QC
The suits of the top four cards are in reverse order to the bottom four. So as you can see, the arrangement can be made to look like a random one. Before discarding the pack, remove the Jack of Hearts, saying that he represents Cupid. Place Cupid face up on the table.
2. Show the packet of cards to the audience, pointing out that they are the Kings and Queens. I'll leave the main presentation to the reader. Turn the packet face down and give it to a spectator and tell him to deal the cards into two piles, dealing to and fro as in a two-handed game of cards. Then tell him to pick up either pile—drop it on top of the other, then pick the packet up.
The spectator can now carry out the above process as many times as he wishes until he is satisfied that the cards are in an unknown order. He now carries out the following procedure:
A) He deals the cards into piles again. Then, he picks up Cupid and places him face up on top of either pile. Finally, he drops the other pile on top of Cupid to bury him.
B) You now spread the packet on the table and slide out the face-up Cupid along with the two cards on either side. Remove Cupid from between the two cards and place him face up on the table. Close up the remaining spread and give it to the spectator.
Steps A) and B) are now repeated two more times. This will result in two more face-down pairs of cards, plus the final pair, which you ask the spectator to lay on the table beside the other three.
3. Conclude by tapping each pair with Cupid before turning them over one by one to reveal four perfect marriages!