Fiore is a lonely alien who takes great strength from his friendship with Mamoru Chiba, spending many years searching for a worthy flower for Mamoru. He had arrived on Earth at around the same time that Mamoru's parents had died. The two boys became close friends at this time, but Earth's atmosphere was unsuitable for Fiore to breathe, so he had to leave Earth.
Mamoru gives him the gift of a rose, and Fiore resolves to return some day with a worthy flower for Mamoru. This quest for a flower puts him in the path of the Xenian flower.
Fiore's character was similar to Ail and Ann, the Makaiju children from the first arc of Sailor Moon R. His clothing, which changes several times during the course of the movie, greatly resembles that of the afforementioned characters and he shares a similar history as well as an aversion to the environment on Earth.