When Fi was created by rinsing the host Red of all his impurities, the first thing Fi resolved to do was avenge his comrades, finding the Warden Spite and sending her back to her plane, only to venture to her domain and find himself overextending. They battle again, and through his energies he subdues her and forces her to bow to his will. When this does not work, he pledges to make her life a living Hell, and still regularly cripples Spite's power as an act of vengeance.
When he is well into his realization of his power, he meets Nahkriin and Tetsuya, joining the X-Heroes for a time. When he defends Apur from the Eclipse, a band of rogue Nightmares, he leaves the team and brings in his replacement, then going on to confronting the other half of him that was cast away. Once he defeats the beasts plauging Mai, he observes his powers and departs, promising him the support he needs to live his now eternal life.
