The only sighting of Fluffy during the Convergence itself was made by a small group of elves in the final days of the forty-day event, as they fled into the deep forest beneath the shadow of the Jagged Mountains to escape the lethal red light. The account, preserved in fragments through Darkmane ancestral tradition, describes the fleeing survivors looking back through the canopy and seeing, in the sky above the open land they had just left — still burning with the Convergence light — a shape that was not the star and not the light and not anything they had a name for.
The elves did not stop. They had no way to know what they had seen. The account was passed orally through generations of what would become the Darkmane Elves, and by the time it entered any written form, the specific details had blurred into impressionistic description: something large, something patient, something watching. It did not follow them into the forest. It did not intervene in the Convergence. It watched.
See The Five Public Appearances of Fluffy for the full account of all five sightings.