Rocket's immediate reaction to seeing his pseudo-son from across the room is elation. He's practically running on all fours to get across the room to him, only to stop six feet from him when he realizes what's going on here.

Dad Mode activated.

"Put that down or so help me," Rocket snaps, crossing his arms over his chest. Yeah, hi Groot. He'll get to the joy at having you here momentarily, but right now he's making sure you don't get drunk.