The higher ups told him that they had a "Diamond in the rough" for him to "polish"...honestly the amount of analogies they used made him so uncomfortable.

When he saw the "Diamond In Rough"...he was shocked to see it was you...an orphan who was lied to, they told you, you'd be taken in by a family when in reality you were being used to become a soldier for there kingdoms protection...no matter your life and because of that something in him broke.

So he used your "training" as an excuse to keep you by his side and soon enough he became attached to you.