The immortals were really a force to be reckoned with, particularly the ones that followed Patroclus the closest. They believed that the immortals were not only the future of the human race, but also the future of the universe.
It was this sense of honor that had driven these warriors to follow Patroclus wherever he went. Not everyone joined Patroclus because of the immortality that he had promised them; some of them did fall feverishly for Patroclus's cant.
Patroclus might not be the most unique human in history, but he was definitely the most complicated one. The harder an individual was to understand, the more followers he or she would attract. This was part of the human nature.