A pact with the devil -- but who's the devil?

It seems as if Speaker of the House Ryan has done nothing but criticize Donald Trump since giving the presumptive Republican presidential nominee a tepid endorsement. Most notably, Ryan slammed Trump for outright racism for the candidate's criticism of the "Mexican" judge in the Trump University case. While the Orlando massacre would appear to strengthen  Trump's position with voters, his response to it seems to have weakened his position with the Republican party. Some of his ideas apparently violate their appreciation of individual liberty and the rule of law just as much as they offend sensibilities on the other side of the aisle. You still hear Republicans wishing for an "open convention" where Trump could be deposed, apparently forgetting Trump's threats of undefined reprisal from his faithful should that happen. Other observers have assured themselves that a Republican Congress will be as capable of obstructing President Trump, should it come to that, as they've been capable of obstructing President Obama. But would it be as easy as that? Remember the terms of Ryan's endorsement. He's going to vote for Trump, he said, because "I'm confident that he'll help turn the House GOP's agenda into laws." In other words, Ryan has been willing to tolerate a lot from Trump on the expectation that he, unlike Obama, will sign radical Tea-Party style legislation. Partisanship is a two-way street, however. Doesn't Trump have an equal right to expect that a Republican Congress will ratify his agenda? This expectation matters if it proves, as seems likely, that Trump's agenda and Ryan's are two separate things. If the condition of Ryan's endorsement is that Trump sign Ryan's bills, hasn't Trump an equal right to set conditions, given how Ryan and his caucus expect to ride the billionaire's coattails? Does anyone doubt that the self-styled master of "the deal" would demand a quid-pro-quo from congressional Republicans, demanding that they enact his agenda through legislation in return for signing off on their agenda? What would Ryan and the GOP do then? What if they're told they get no budget bill, no regulatory reform, no entitlement reform, unless they pass a bill to build the Mexican Wall, curtail immigration, etc.? Would they sacrifice their agenda to block Trump? It would depend on his ability to arrange for Republican opponents to be primaried for their sins against him. So far I see little sign of Trump arranging to have candidates run for Congress who are loyal to him first, the party second. That's the typical failing of the insurgent presidential candidate, but if he wins his election this year and the conflict between him and the congressional GOP proves irrepressible, the 2018 elections should prove very interesting before the Democrats even get involved. I wouldn't put it past today's Republicans to opt for gridlock, since they're always ready to opt on ideological principles against getting things done, but the x factor they may need to consider before starting that game again is the mood of the country, which Trump, like all modern Presidents, will claim to represent more faithfully than anyone in Congress or Congress as a whole. On the other hand, congressional Republicans have never been impressed by presidential mandates. All of this means that the Republican party could be in big trouble even if Trump wins the November election. It might be very entertaining to watch -- except for the chance of collateral damage, that is.