A Conservative Party-Democratic Unionist Party arrangement brings Northern Ireland’s current political situation into question. At the moment the power-sharing Assembly that was established as a result of the 1998 Good Friday Agreement is suspended. The basic issue is a lack of trust between Sinn Fein and the DUP. Power now rests with the Westminster government (in the shape of the Secretary of State for Northern Ireland). So what happens now if the DUP is effectively part of the Government? The ambition of power-sharing lies at the heart of the Good Friday Agreement and the series of institutions that stem from it. Is that ambition now to be set aside by the British Government?
Throughout the peace process, the British and Irish government have held the roles of brokers (albeit interested brokers) in mediating between the parties in Northern Ireland. So if one of the Northern Ireland parties is effectively a member of the British Government that mediation role is jeopardised.
The timeline between the close of polls and the declaration of a new governing arrangement suggests that these issues have not been thought through.
rogermacginty 
DUP will have leverage, as befits their confidence and supply agreement.
This leverage may be short term if another election is called over the next few months. Very possible. There is no palpable legitimacy for this government. This is not Con-Dems part 2.
Currently we have a volatile and restive electorate, senior Conservatives eyeing May’s back as a knife rack, swivel eyed Hard Brexiteer backwoodsmen monitoring backsliding, and Brexit negotiations ahead of us. This UK government will be held together with pound shop sticky tape and string. Many internal and external pressures will pull at it.
And ultimately – so what? Sinn Fein may have ministerial positions at the next Irish general election, never mind a confidence and supply arrangement. Whither the Irish government as mediators and interested brokers then? That’s a much more lasting proposition.
Another so what – Sinn Fein and the DUP have not shown much interest in restoring power sharing to date. This election will have further lessened that interest. Moreover, large chunks of the electorate are singularly unconcerned about power sharing because they don’t like sharing with Sinn Fein, or dislike the DUP, or think that a DUP-SF partnership is inherently unstable. So what’s to mediate anyway?
Also, the softer edged party variants of Unionism and Nationalism are now dead, in terms of meaningful influence. And they were the unionist and nationalist forces that built the structures of the GFA.
For Northern Ireland, there are far deeper problems at work than this short term, risky, DUP back scratching. Its just the cherry on the top.
For any interested readers – wish list of what the DUP wanted from a confidence and supply style relationship a couple of years ago. Will have to scale it back as they have only one buyer now.
http://www.mydup.com/publications/view/the-northern-ireland-plan