Fyyl was a Bolian Starfleet ensign assigned to security detail at Utopia Planitia Fleet Yards. He was on duty in April 2382 when a Breen agent who infiltrated the station was escaping with captured intelligence on Quantum slipstream drive technology. He was killed by an explosion set to coincide with the agent's beam-out.

Fyyl was described as thin and young, having graduated from Starfleet Academy less than a year prior. (ST novel: Zero Sum Game)