HotPie85

It looked like the horse of the Golden Companies commander?

My thinking of this was that they have had some prior discussion and have come to a plan themselves regardless of what Tyrion or Jon are saying. When she says to Grey Worm "you know when" or to that effect is that its as if she had already decided what she was going to do. "The Bell" was the trigger for her and for Grey Worm to exact revenge.