*Napoleon accepts Frankfurt Proposals in late 1813, ending Napoleonic Wars with him still on the throne
*Spain makes peace via the Treaty of Valencay as per OTL but the British misinterpretation of the Frankfurt Proposal leniency causes British troops to linger in Spain
*British looting later blamed on 18th Hussars given their situation after the Battle of Vitoria, Ferdinand VII is psychologically broken after Napoleon fails to escape responsibility and the Spanish jewels stolen by Joseph Bonaparte are never recovered.
*Ferdinand repeals the Constitution of Cadiz in early 1814 and loses popular Basque support as their autonomy is lost in favor of a more central absolute monarchy, the popular reaction against him furthers his depression.
*Carlos V of Bourbon (he has the latter added to avoid confusion with the more famous ancestor) takes over as regent in 1814 and full king on his brother's 'mysterious' death in 1815, many theories somehow involve 'the French'. Carlos is more pragmatic and feels abandoned by his former English allies while but Spain avoids the Carlist Wars altogether.
*Carlos takes a more direct but less firm hand in those areas of South and Central America still under Spanish control while advocating for peace, he retains OTL Ecuador, Bolivia, Peru, Uruguay, and retaking Argentina by an invasion of Buenos Aires. Paraguay remains independent as a border state and becomes a hotbed of activity for pro-independence movements throughout South America (This leads to Carlos and Pedro of Brazil isolating the province and its return to Spain via the Treaty of Lisbon in 1844). Chile is brought back into the hegemony with a treaty respecting 'autonomy' but realistically is made part of the renewed Viceroy of La Plata. Each colony is given more autonomy under local control but answers to a royal governor and royal council located on the shores of Lake Titicaca. Interestingly, Carlos opts to attract more European settlers here during this time, especially in areas controlled by his supporters in Spain and other Catholic countries.
*Mexico, Central America, and the rest of Gran Colombia are allowed to leave but close economic ties to Spain itself emerge over the next decade.
*Carlos stands aside as the Liberal Wars in Portugal rip the country apart then moves his own forces in to take command of Portugal itself in 1835. Decried by much of Europe, the unpopular monarchs of both sides are unable to rally much against Carlos outside of Porto which finally falls entirely in 1836. Brazil sanctions the country until its own Treaty less than a decade later, fears of civil war broil to the surface but Carlos squashes any potential organized opposition in the Peninsula early. Portugal's colonies also come under Spanish control, but Carlos is careful to actually listen to his Portuguese part of the Cortes.