So that's what future meant about not being able to "Change" Aki's fate no matter what happens. Aki referred to Makima for help to change his fate, which made him have a contract with the gun devil. Little did he know that despite doing that, he never changed his fate. It was all planned. Then there goes Power.
I was five and he was six
We rode on horses made of sticks
He wore black and I wore white
He would always win the fight
Bang bang, he shot me down
Bang bang, I hit the ground
Bang bang, that awful sound
Bang bang, my baby shot me down