I believe I have settled on my PoD, and I shall be doing the survival of Miguel da Paz. The interest in Spain and Portugal being united is certainly interesting and I've already pondered about several things stemming from it.
- Most importantly, Portugal, Castile, and Aragon will be united in one person by 1521, when Manuel I dies. Assuming Isabella doesn't die in childbirth, she'll rule Castile in 1504, and Aragon in 1516. I'd expect her to be fairly dominated by husband and he'd call the shots; after he dies, Miguel would become co-ruler with his mother. If Isabella dies in childbirth in 1498 as she did in OTL, and Miguel simply survives, then Miguel's father will no doubt serve as regent for his young son.
- Tolerance for the Jews? Manuel was quite tolerant of them, he only expelled them from Portugal in order to marry Isabella, Miguel's mother. Once he comes to rule over Spain, is it possible he reverses the Alhambra decree and allows Jews to settle in Iberia again? Even after his marriage, he executed those who started an anti-Jewish riot in 1504.
- Isabella's confessor, the Archbishop of Toledo, Csnieros, probably finds himself out of a job in an Aviz dominated Iberia...
- Yet on the other hand, in 1515 and onward, Manuel asks for the Pope to allow the formation of the Inquisition in Portugal. If he comes to rule Spain through his wife, or for his son, the Spanish Inquisition may be expanded into Portugal. It's powers could be cut back, however, especially if Manuel chooses to reverse some of the unsavory policies of the Catholic monarchs, especially regarding the Jews.
- The Iberian monarchy is going to be a rising star, no doubt, with the Portuguese trade routes in the East, in India and Asia, and the Treaty of Tordsillas which has essentially named the Americas as a whole a possession of Iberia. The Aviz monarchy is essentially going to be a hyper-power, but it's going to have trouble dividing it's interests in Asia, and the Americas, and the interests of the constituent portions of the monarchy. The idle noblility of Castille who IOTL played a part in creating the Spanish Empire are going to need something to do and will push for the same things, while commercial interests in Lisbon will find more interest in maintaining the Portuguese empire. The Aviz will be a hyper-power for awhile, but as Spain and Portugal both declined after their heydey, the crash will probably be quite bad, but good for their rivals in Europe.
- The Italian wars will still occur, as Aragon was tied to Italy and that will bring Portugal in against France's ambitions. But the Aviz will definately take a different route in dealing with it; who knows if this state has the energy to bash down the French, and deal with maintaing an empire in Africa and Asia, WHILE attempting to tame the Americas. Lots of divided interests, and lots of juicy fun.