We know that Alison had a genuine mental link with Number 6, so that when Number 6 holds up his five cards, she is reading his mind, but deliberately calls out four wrong cards. It’s a pity that it only worked with cards, otherwise they could have picked up on what each other was thinking! But that only works when two people know each other very well, have lived with each other, and come to know what the other is thinking. But perhaps that does happen, because when posing as Curtis Number 6 takes a cigarette lighter from his pocket, before Alison takes a cigarette from the box, in order to light it for her. So if Number 6 could do that, perhaps he knew that Alison was faking the miss-reading of his cards, but did not dare show it. After all when Alison came to see Number 6 off, she knew it was him, and told him that what she had done was a betrayal, and that if she had a second chance she wouldn’t do it again. But then Number 6 asked her that isn’t everything we do here a betrayal, possibly meaning that he betrayed her in knowing her thoughts, but not daring to show it because of the danger of betraying himself!
Be seeing you