[For Yugi, it was painless. Like swapping who was 1st player in a game. For Ryou, it rendered him unconscious. Yugi and the Pharaoh co-existed. Ryou and Bakura did not.

Marik hums in thought. Although he doesn't fully trust either of them, Yugi was good at keeping secrets when he needed.]

Yugi's capable of handling himself. It's... up to you if you want to tell him. From what I've gathered, he's pretty good at dealing with secrets considering most don't know the Pharaoh even exists.