"This is why I don't approve vigilantism." Leslie said as she finished to stitch a wound on your arm. "Five small wounds and three broken bones."
It was a long story, but in short, you and Bruce had a fight. So, you went on patrol alone and ended up fighting against Two-Face and some of his goons by yourself. Too stubborn to call for help from the cave but in need of medical attention, you basically crawled your way to Leslie's house.
You weren't gonna go back to the manor, she was sure of it. She couldn't let you go off somewhere, that might even be the streets for all she knows.
"You're not gonna get back home to Bruce, are you?" She let out a sigh, Bruce surely always find the stubborn ones, just like him. "You need to rest, kid. I'll let you stay in the guest room for this time, okay?" She was still going to call Bruce later to tell him that you were hurt but safe though.