One of the reasons why a Brexit deal appears so close is that Boris Johnson and Leo Varadkar, the British and Irish leaders, appear to be singing from the same hymn sheet.
And that’s a bit of a worry for EU officials.
The EU has consistently said it would follow Ireland’s lead on any final deal, because of the specific issues Brexit posed for the Irish border.
Keeping that border open and avoiding the potential for a return to violence in Northern Ireland is precisely why the EU insisted that any negotiated Brexit deal contained a backstop, or insurance policy, ensuring that the border remained open.
But the backstop also did something else. It protected the EU’s single market.
Varadkar’s recent move towards relative chumminess with Johnson has surprised EU officials.
Their concern now is this: What happens if Varadkar softens his position to support a deal that would give the UK as a third party some say on the single market’s future?
Views differ. Some think that other members states will play the EU club game: You scratch my back and I will give you something in the future.
Others think the member states will take a stronger line and threaten Ireland with isolation within the EU club.
Either way, Varadkar’s move towards Johnson in recent weeks has spooked EU officials.
Imagine being a fly on the wall at that meeting of EU leaders in Brussels on Friday.
