Guillaume Gelinas, 22, was formally charged on Monday at a courthouse north of Montreal.
He is accused in the deaths of Luc Gelinas, 54, and Julie Lemieux, 35.
Television cameras caught Gelinas emerging from a prison bus at the Joliette courthouse on Monday wearing grey sweat pants and a grey T-shirt.
He stood motionless in the prisoner's dock as he appeared briefly before a judge after spending the weekend in detention.
Gelinas' case was put off until March 6. He will remain behind bars for the time being.
A Canadian Forces official confirmed the accused was a reservist who joined the military in June 2007. It is unclear whether Gelinas is still a member or what rank he held.
Gelinas's record indicates he was stationed in Afghanistan from November 2010 until July 2011.
The military could not provide much more information due to the ongoing police investigation.
In July 2011, Luc Gelinas wrote that his son had finally returned from Afghanistan after eight months.
"We're proud of him and very happy that he is back with us," the elder Gelinas wrote. A picture of the victims with the accused was posted to the father's page that same day.
Luc Gelinas had three children, including the accused, from a previous relationship.
Police found the victims in their home on Thursday morning in Terrebonne, north of Montreal. It was the elder Gelinas' birthday.
Guillaume Gelinas was arrested on Friday after being questioned by investigators.
Police had spent the better part of Thursday looking for him before tracking him down in Gatineau, which the accused listed on social media as his hometown.
He was charged over the phone Friday night with two counts of murder.
Lawyers presiding over the case for the Crown and the defence kept their comments brief Monday.
The Crown would only say that a portion of the evidence has been given to Guillaume Gelinas' lawyer. The latter was just as reluctant to talk.
"I won't go into the discussions I had with my client," said defence lawyer Jonathan Meunier.
"Yes, I spoke to him of course. We have to deal with his case and that's the first concern at this stage."
Both victims worked in management for Quebec's liquor board.
(Cogeco/The Canadian Press)