Justin was born on Crest on September 12th, 2545. When Crest was attacked in late 2551, Justin lost his mother. He and his father, Joseph Ryder, managed to escape the planet and survive the glassing alongside a third of the Crest population. He was then taken into the Spartan Program a year later.
Hunting Arthur Banks
"He's a great soldier, leader, and friend. What's more to ask for?"
―Justin-D009, during a conversation with Kyle-B115 about the successes of Team Hadron.
Justin has a strong friendship with Oliver, and trusts Oliver to make the right decisions during missions. He almost always takes Oliver's side during arguments, and expects his friend to do the same. Oliver also puts Justin in charge of the other half of the team when they must split up.
"To be honest, I don't know her that well... with me being in front with Liv and she being a mile away and everything."
―Justin, about how Rachel is distant from the team, both physically and socially.
Due to Rachel's lack of social interaction, Justin does not know much about her. She rarely speaks to him, even when the rest of the members aren't nearby. Her shy nature makes her an almost polar opposite of Justin, and her distance from the team during missions means that Justin rarely sees her during operations.