"I lost six years of my memory recently, but from what I pieced together from Rex and various reports, I worked for Providence since not long after the Event. Got hired on to deal with the 'monster' issue: killing them or bringing them back to be molecularly disassembled for the head research scientist at the time. I found Rex four years after the Event after encountering a massive biomechanical EVO. Kid saved my life by actually managing to cure an EVO I was distracting to give the kid time to get away. He only remembered his name at the time.

"Ended up becoming his partner, training him and working alongside him in the field."

And apparently the closest thing the kid remembered to a father as sad as that was. And as much as he trusted Smith, he was not going to tell him his other orders.