There is a lesson to the unexpected spectacle of the DUP/Sinn Fein power-sharing setup.
That is that a peace agreement has to be negotiated between the parties that are actually fighting. Distantly related proxies can negotiate all they want, but ultimately it's what the conflicting parties themselves will accept that matters.
The initial peace negotiations in Northern Ireland were outside the political institutions, and they set the framework for the new regime. But at that stage it was still tentative.
The government formed by Trimble and Hume was not able to settle matters, because neither was able to satisfy the other side that was speaking for the hardliners. John Hume could not satisfy Unionists that the IRA was on board, because he doesn't speak for the IRA. And Trimble could not satisfy Nationalists that the unionists were permanently committed to the new arrangements, because he could be overruled at any election by Paisley being elected.
So when commentators ask, how can Paisley make a deal that he attacked Trimble for making, the answer is that Paisley is making a deal via Sinn Fein with the IRA, not with the SDLP. And no deal with the SDLP is a deal for peace, because the SDLP was never at war.