Just when you think you can't be surprised, along comes a whopping reminder of how fractious Northern Ireland politics remains.
For all the smiling consensus at joint press conferences there was always that sense of key players on both sides waiting for the other to make the sort of mistake which allows them to jump in and reheat old arguments.
Michelle O'Neill dumped a huge problem on Arlene Foster's doorstep on Tuesday: but it was the sort of problem that Foster hoped might end in a fudge and something that could be interpreted as an apology.
But O'Neill wasn't for budging. And it soon became clear that there were elements within the DUP which wanted to extract a form of revenge on Sinn Fein for all the blows landed on their leader during the RHI crisis.
Foster refused to mention the 'resign' word on Wednesday. Partly because she knows that it reopens the arguments about her refusal to do so back in 2017 (which led to McGuinness's resignation, the collapse of the Executive, an election which saw unionism lose its overall majority and three years without devolution); and partly because she knows that if O'Neill treads the path she herself trod in 2017, by not stepping aside for a few weeks, history could easily repeat itself.
So it must have come as quite a blow when Lord Morrow and Lord McCrea (popular and influential figures within the party) issued a blistering statement last night, demanding the resignation of both O'Neill and Conor Murphy.
That blow was amplified this morning when Jeffrey Donaldson, the party's parliamentary leader, also called for O'Neill's resignation.
The problem for Foster is this: if O'Neill refuses to go what does she do?
She could wait and see if a motion of no confidence - and the leaders of the SDLP, UUP, Alliance and TUV have all called for O'Neill to go - was passed, which would put greater and broader pressure on her; and SF doesn't have the numbers to play the petition-of-concern defence card this time.
Failing that, the only way to remove O'Neill is to remove herself: but that risks collapsing the Executive and then relying on SF to cut a deal to reboot it.
At this point I think collapse will be avoided (if SF is so minded and O'Neill can deliver some form of credible mea culpa).
But if it does collapse I don't think it will ever be restored.