Backstory: His memory, completely wiped clean by herbs he took from the menders, contained sights that would've haunted him for his life. Understanding that he was traumatized from his experiences, his sister wanted him to live a better life, and so she convinced the menders to help her. Though she didn't know what her brother went though, she didn't want to make matters worse by asking him, since she knew that this was an extremely personal matter. Now, being EXTRA oversensitive and anxious, sometimes, he goes a bit crazy trying to figure out why he feels that a part of him is missing, and why he can't recall anything. In order to stop this, his sister convinced him to join the army to at least try to get him off of his worries and help defend their Allegiance against whatever thing that ruined a part of his life.
I just took the one of the original Scratch backdrops cuz I was out of ideas :P As a young child, when his sister wasn't born yet, he lived in an endless void of terror and scars. His family, separated by the rest of the group by a stray but cunning sleuth of bears. They perused these poor cephilli until they finally managed to return to the group about a cephillis month later. When they reunited, his mother had his little sister, but shortly died after. For his father, he got so crippled when they lived with the bears that he simply just died from his wounds and scars. After living in months of agony, his sister then decided to take action that would change a very large majority of their lives.