A classic satellitist, Fillion grew up in poverty and squalor on the Navarean colony Envilles. His parents were simple workers, hard labourers that worked in the mining facility of Perigard, the capital city of Envilles. As an adult, he joined the Navy in search of an honourable profession that would net him money and respect, but deserted after a traumatic mission that left him the only remaining alive member of his squad.
Fillion is a satellitist. Due to the low gravity and terrible medical systems on his homeworld of Envilles, his bones and muscles have developed stagnantly, causing him to be inhumanly tall at almost 7'3" (220 cm). He is a Navarean, has teal-green hair that's made into a slick back, and unkempt stubble he wears because he thinks it makes him look ruggedly handsome. Fillion is augmented. In an atmospheric flight, he lost control of his ship and crashed onto the surface, leaving the right side of his face heavily scarred and his right eye critically injured.
Even though he does not like the idea of body augmentation, he likes it more than the idea of losing his right eye. So, he replaced his damaged eye with an augmented one, letting him also display a HUD and IR/UV vision. However, it also leaves him with a permanent titanium faceplate implanted into his skull.
Fillion is a gruff hard-boiled veteran who has seen his fair share of battle. After losing his squad, he has developed C-PTSD and is generally distrustful of all authority. It is hard for him to develop a friendship (or a relationship of any kind, for that matter).
During his work aboard Galathea station, he kept up a respectful relationship with the chief of security and something that could arguably be considered a friendship with security officer Harvey Dale.
Over the events of Onyx Black, he learns to trust the people around him and even forms a friendship with Bill Taswell. He is envious of Bill's seemingly perfect life, and because of that, he is willing to protect Bill with his life.
Politically, he believes in the ultimate right to personal liberty and is absolutely disgusted by the chokehold the giant corporations have on colonies like Envilles and sympathises with Sector C-Null as they're trying to unify the galaxy by whatever means possible.