It's been a while since 3.1, but I really do love the Tribios' character and what they represent.
You see, Tribios is the very first demigod, the one responsible for spreading the prophecy of the Flame-Chase Journey to all corners of Amphoreus. A messenger.
But she's just that, a messenger. She doesn't have the might of warriors like Phainon and Mydei, or Anaxagoras' incredible intellect, or Castorice's terrifying powers, or Aglaea's leading skills. She couldn't ever dream of fulfilling the prophecy with her own hands; in fact, she always knew she'd never be able to see it fulfilled.
Yet, she was the first to receive the prophecy. She had to be the one to turn the gears of fate. And she never hesitated in fulfilling her duty. She became the Heir of Passage, and even after her soul split into a thousand pieces, she never faltered. Even when said pieces began fading away one by one, she carried on, carving the path of the Chrysos Heirs with her own feet throughout the ages.
The very first demigod inherited the Coreflame of Passage, and isn't that fitting? Janus is the Titan that governs all roads and paths of Amphoreus. Their authority is the one the Flame-Chase Journey needed the most at the start: the ability to carve a path, the ability to point the way forward.
It's even more fitting that the Tribios are so numerous. Their power has always been the one to guide, and with so many of them, surely they can find the heroes needed to fulfill the prophecy. Surely, they can show the whole world where tomorrow is.