Apparently, there were going to be a lot of surprises today. Bruce could have just seen Jason's hand and he would have recognized him, but the arm, clad in a familiar coat, made identification beyond simple. Mia was already rising to meet him, accepting a crumpled bag before Bruce could even decide what to do. It was nice to know that Jason had someone, a friend, though maybe it was presumptuous to think he didn't have more. For all Bruce knew, Jason had dozens of them - he just didn't think so. And he liked Mia. Enough that he hadn't said a word to Tim about her.
When it was clear that Jason intended to hover just outside the door and go no further, Bruce went to join them, grabbing a spare paintbrush on the way. He didn't say anything, not by way of greeting or instruction, just held out the brush and raised an eyebrow, head tilted sideways into the room. Then, he waited.