Born during the Renaissance, Máximo Barrosa was a dedicated young Assassin recruit who grew up in the same village as Aguilar de Nerha. Máximo was light-footed with a natural ability to move silently and without detection. From a humble peasant upbringing with no ancestry of Assassin heritage, Máximo looked up to Aguilar. He constantly tried his best to imitate him and grew to love him like an older brother.
When Aguilar's parents were burned at the stake by the Templar-backed Inquisition, Máximo was a witness to the horror and shared his friend's grief and anger. Later in his life, when Aguilar returned to his hometown after joining the Brotherhood, he told Máximo of the Creed and their fight against the Inquisition. Eager to follow in his friend's footsteps, Máximo decided to join the Brotherhood as well.
- "Máximo" is a Spanish dimunitive of the Latin Maximus meaning "greatest". The surname "Barroso" is a Spanish surname derived from barrera which referred to a barrier and denoted that the family originally lived beside a gate or fence.