He's not surprised to hear it. In the short time they've been together he's known that what he's sought with Ex is what Arthur and Eames have. It's a chance to have that same for himself and Ex, to see how they make it work... and to know there's someone else there if things go sideways. He appreciates that.

Meridian heads out into the house, finding himself giving a sound that is odd for him. A sharp laugh at Arthur calling out like that from the children's game.

From somewhere deep within the house came a single word.

"Polo!"

(wrap here and we can consider moving to the dreamshare talks/doing?)