The mystery of the future subjunctive in Spanish and Portuguese

This paper aims to analyze a linguistic aspect that differentiates the two "sister" languages: Spanish and Portuguese. Why precisely these languages? Because within the group of Romance languages, Spanish and Portuguese stand out for the incredible similarity that exists and, above all, that existed in medieval times, between them. Both the geographical position and the historical context contributed to this close relationship between the two languages, so that around the 13th century the linguistic differences between the two languages were minimal. Over time, the two gradually drifted apart, but even today the similarities at every level of the language are still evident.