You were adopted by the Waye family when you were 14 and Dick was 15.
You were there for most of what happened...but you weren't a vigilante, you never really wanted to be one. You just wanted to live your life peacefully.
You were close with Dick and Jason. Friends with Tim. You and Barbara were good friends two. And it seemed like you and Damian got along just fine. Cass saw you as a close friend too.
But when Damian was 11...Bruce snapped at you, he thought you were lazy, apathetic, and rude...though you really weren't...he gave you an ultimatum. Since it was obvious you weren't going to join them...you had to join the army or get thrown out with nowhere to go...no money, no connection to the family.
It was put your life on the line...or be homeless for who knows how long, possibly dying from illness, the cold, or even being killed all alone.
So, you didn't have a choice...you had to...Everyone even Alfred tried to talk him out of it...but in regular old Bruce fashion, he was stubborn and realized it was wrong and he was wrong too late.
And Bruce's relationship with everyone, even Alfred was strained afterwards...if it wasn't for Alfred, Jason wouldn't be around the family anymore.
They already took you away...you couldn't contact people for a while...and when you did. You wouldn't contact them much...and would barely connect Bruce if you even did.
After training you were quickly taken into war...You were in the 15th group...the number that was unlucky to you...and it stayed unlucky because...You almost died a lot, lost many friends, killed many...even some children but you had no choice and you hate yourself deeply for it...you have multiple scars...and after just four years you were honorably discharged from any and all future wars...you have a permanent limp. You have Nerve damage from scrap metal flying into your arms...one is worse then the other...which hit something giving you nerve damage in your hands, you can hold a pencil but not still at the moment let alone a gun but you can at least write again if you continue with physical therapy...you spill a lot of your drinks at the moment so you usually get one with a lid...or it has to be cold so you don't burn yourself.
You were given a choice after being discharged...you can get a ticket to go home or go to a different place and live in a home for military and ex military, until you're able to live on your own again...and get back on your feet.
[Start how you want and your choice if you told them about your injuries and if you told them about the existence of your injuries.]