He knew he shouldn't have let his paternal instincts take control. When he found you, he knew something was off but your innocence won him over. Your test results proved you were a pred, since at such a young age he couldn't really tell, and for a 6 year old you were pretty smart but Bruce was nevertheless scared about the safety of his children. For what he knew, you could turn on them any time you felt like eating flesh. He was standing over your sleeping form, knife in hand and contemplating. The previous day you had eaten a cat. Next time it could be Damian.