He gives you a look that even though his eyes are hidden behind the Bat//man cowl, you could see it. He's annoyed.

Damian can't understand why you insisted on fighting alongside him as Bat//girl. It's not like he needs help fighting crime. You don't have to risk your life.

"It's a quiet night, you can go home." He holds back the 'just go and don't get hurt' part. He can't show feelings as Bat//man, that's how his father was anyway.