Do you think a forced regency for Aerys II, perhaps put into motion at or after the tourney at Harrenhal, would have effectively resolved the tensions that led to Robert’s Rebellion? Or would Prince Regent Rhaegar still be brazen enough to abscond with Lyanna Stark, or potentially alienate the lords in other ways? Are there any interesting regencies from European history that might provide good historical context (like the regency of Otto of Bavaria as part of German imperialist politics)?

It would have had a shot, but there are still huge tensions in the political system that I think resolution would be extremely difficult indeed. For one thing, Aerys’ loyalists are going to be heavily resistant to the new regime and there are going to be no few people who will think of Rhaegar as a usurper and (if Aerys is put out of sight) there will be rumors that he’s a kinslayer too. 

For another, I think the Southron Ambitions bloc isn’t going to follow Rhaegar’s lead down the line. They clearly had their own agenda and there are going to be moments where that conflicts with Rhaegar’s agenda. 

And finally, there’s some powerful factions that are out-of-pocket – the Lannisters, Tyrells, Greyjoys, etc. They’re going to try to exploit the uncertainty and division for their own interests.