Sibling Rivalry
Very rare1.4%Starting as any of the Jimena siblings in 1066, become Emperor of Spain
Start as one of the Jimena siblings in 1066 - Sancho II of Castille, Alfonso VI of León or García of Galicia - and end holding the Empire of Spain. Alfonso VI is the pick (best Intrigue): murder both brothers early (agents may refuse plots in the first few months - persist), press your claim on Navarra, then take the Unite the Spanish Thrones decision to merge the kingdoms and expand until the Empire of Hispania is creatable. Two Fate of Iberia warnings: either disable the DLC (so you needn't end the Struggle before forming Hispania), or play to any Struggle ending EXCEPT Status Quo - that one destroys the Hispania title. It doesn't need to fit one lifetime; the dynasty carrying on is fine.