The Lusiads
Os Lusíadas, in its original language, is the Portuguese national epic, written by Luís Vaz De Camões and originally published in 1572. An epic written as a union of history and the legendary, Os Lusíadas recounts the fantastical Portuguese voyage of discovery of the route from Europe to India by sea, and exalts the many remarkable and grand episodes of Portuguese history, bringing out the virtues of the Portuguese.
The hero of this tale is in fact, not a single character, but the Lusiads (Lusíadas), the sons of Lusus, or in other words, the Portuguese People. The epic was dedicated by its author to king Sebastião I, and to the valiant efforts of the Portuguese sailors and navigators throughout the age of discoveries, particularly Vasco Da Gama, who lead the expedition that succeeded in discovering the sea route to India from Europe.
Many characters and historical personae of Portugal are depicted and glorified in Os Lusíadas, as well as countless nameless countrymen who participated in the kingdom's endeavors and achievements; and although Vasco Da Gama is the most featured of the named characters and closest to a central position in the epic, he is not the sole protagonist, but rather stands in for the true hero, the Portuguese people. As such he is the representative of all the greatest values of the Portuguese, from their bravery to their boldness and determination, embodying all the qualities that they take pride in.
The importance and reverence given to the work of Luís De Camões is something that both strengthened and altered the legend surrounding Vasco Da Gama.
Due to this, the true identity of Servant Rider is not just Heroic Spirit Vasco Da Gama, but also a grand collective of Portuguese wraiths involved in their feats as a people.
Collective Hero
Rider is an irregular Heroic Spirit that is composed of not only the soul of Vasco Da Gama himself, but also of the innumerous wraiths of all the Portuguese who played a part in the era of discoveries of Portugal, which together embody the spirit of the Portuguese people itself. Due to this special characteristic, Gama's very image is different. His personality differs from what it was in life, being closer to a caricature shaped by historical anecdotes and representing the ideal Portuguese traits, and he possesses skills and power he did not have in life. As he is empowered by the souls of many wraiths, his parameters and power as a Servant are drastically superior to what he should've been able to achieve with his legend alone.
He is a hero that is composed by many mentioned, but nameless, smaller, more mundane heroes. The sailors and navigators who played a part in the age of discovery of Portugal cannot be called exceptional as individuals. It was in the grander ideal, followed by their united souls that extraordinary worth was found. They were not otherworldly warriors or practitioners of the mystic arts, but simple people who banded together for common goals, who managed to overcome fate by working together and enduring their hardships with bravery and determination.
This Heroic Spirit is, then, a collective hero with the joined strengths of all those that were part of his legend.
If Rider were to be summoned in Portugal, he would benefit from a fame boost that would allow him to contend evenly with the greatest heroes of humanity throughout history. Additionally, he would further draw power from the presence of the people he represents, and the traits still found in them to this day that he proudly exhibits.